I'm in the process of writing a campaign in a homebrew world, and I have my main villains set out. However, I would like some bad guys to use for sidequests, etc. That's where you come in. Who's the best bad guy you've ever created? Some rules:

1. No tragic villains you don't want to kill. I want villains you love to hate, not good guys who are only robbing so they can afford medicine for their puppy.

2. No BBEGs. I want sidequest villains. 

Honestly: well played party of rival adventurers that match (or are very close) to power level of your players. They can keep messing with your group over and over again.

Also have a party of rival adventurers that antagonizes my party when they show up, they were initially beaten at the start even though they were all a level or two higher and have stuck around since the start.

Right now I actually have a banker who is my side villain, early on my players won way more money than they could ever spend. Instead of having them just buy up everything they'd ever need I made him to force a contract on them. They either need to purposely limit their spending to not mess with a local economy and throw it out of balance (they'd get interest out of it was the selling point), or they could keep all their money (and I'd have the bank send assassins after them to stop a possible economic inflation). Since they sided with the banker and signed the contract though I'm adding another layer to where they money they've been using so far has been the bankers personal fund, and he will run off with their mountain of gold and fund a vampiric uprising.

One of my more recent side quest villains though was a bardic goblin in a labyrinth who held a small child hostage and was going to attempt a blood sacrifice ritual at an appointed time to gain the grand magical powers of a being known as "Ziggy". So movie references might be fun to mess around with if your going for a lighter inbetween campaign session(s).

Sounds like great villains! One-upping is something players hate, and stealing money from them is just evil.

Keep 'em coming, everybody!

Honestly imho "best villain you ever created" and "side villain, not BBEG" don't exactly go together.  So here's a gallery of villains which are not my best, not even tier B, but which are all simple conceps which don't require more than 1 offs to deal with.

- A city has a bunch of children that have been going missing.  Originally it's only been the poor, but lately some children of wealthier folks have been going missing as well, which has drawn significant attention, so now the city is looking for help.  The villain?  A greedy merchant running a slavers guild who has been orchestrating the kidnapping of those children and their sale to forces for use in demonic rituals.  Because some people are just that large of dbags.  Bonus:  Can lead to the PCs wanting to track down and exterminate the cultists running the demonic rituals, or at least figure out what they're up to, providing an easy "step up" villain opportunity.

- A town had a minor bounty for the extermination of a den of kobolds, say 500 gold.  Yet that bounty has been reposted time and time again, increasing each time, as adventurers take it only to never return.  Now it's gotten up to an amount of gold best described as "interesting".  The villain?  A regular kobold, but an absolute MASTER of traps.  His den has been fitted with more deadly traps than you could shake a fist at.  This provides great opportunities as well for the whole "notes on corpses" lore building if you're into that thing (I am), and a chance to flex your puzzle building muscles.  Be sure to throw a few clever twists in there too- such as, the doors have very simple puzzles or riddles indicating the correct path, but the "correct" solutions are all trapped and the untrapped path is the one which is offset one to the left or right of the riddle's solution.

- A town has been having many of its residents performing strange and / or terrible acts, and then once imprisoned swearing up and down they didn't do it, despite being caught red handed.  Several high ranking officials even have been suddenly turning on those closest to them or performing acts totally out of character, and they swear there must be some other force at work.  The villain?  A necromancer who has seized control over the ghosts which inhabit the graveyard, and is using them to possess people while they sleep.  His motivation?  Pure chaos, a worship of a chaos deity which makes him want to cause as much mayhem, destruction, and sorrow as possible.

- The party has been having an image problem.  EVERYWHERE they go, their name is just getting dragged through the mud.  People they interact with get robbed, assaulted, or worse, and whenever there are witnesses, they swear it was a member of the party.  They can subsequently prove their innocence, but it's beginning to get on their nerves.  The villain?  Their mount!  A Doppleganger Druid has been posing as one of their horses (or if they don't have mounts just following them around as an animal) and then posing as them and causing mischief in their wake.  Apparently they messed up some plans the Doppleganger had, like WAY back, and this thing just doesn't know how to let it go.

- The party was sent to retrieve an item from some ruin.  It wasn't that big of a deal.  There was this annoying snake thing that put up a pretty good fight, but they beat it, retrieved the item, and washed their hands of the affair.  Didn't they?  The villain?  The spirit naga!  This can be uncorked after pretty much any dungeon, the thing just won't die, no matter how many times they kill it, and it seems hellbent on chasing after them as soon as it comes back and attacking them again, and again, and again.  Ultimately they'll have to do *something* other than just kill it, whether that's trapping it or whatever, and that's easier said than done with a creature with dimension door and the ability to dominate any prospective captors.  Note:  This does require giving it some means of tracking the party, whether that's a scrying spell or whatever.  Still, if you want something the party will come to LOVE to hate, this is the one right here.

There's 5, hope that's helpful!

Goblin Dick

Originally the imaginary foe of a not very bright noble fighter, who was taunted by the peasants that his lady loved Goblin Dick, so he set out to find and kill his rival. He never did, and eventually retired to the family estates, famous for its cider presses, only to find Goblin Dick and his Apple Scrumpers we're raiding the orchid.

Goblin Dick has yet to be beaten.

Quote from GiantOctopodes >>

Honestly imho "best villain you ever created" and "side villain, not BBEG" don't exactly go together.  So here's a gallery of villains which are not my best, not even tier B, but which are all simple conceps which don't require more than 1 offs to deal with.

- A city has a bunch of children that have been going missing.  Originally it's only been the poor, but lately some children of wealthier folks have been going missing as well, which has drawn significant attention, so now the city is looking for help.  The villain?  A greedy merchant running a slavers guild who has been orchestrating the kidnapping of those children and their sale to forces for use in demonic rituals.  Because some people are just that large of dbags.  Bonus:  Can lead to the PCs wanting to track down and exterminate the cultists running the demonic rituals, or at least figure out what they're up to, providing an easy "step up" villain opportunity.

- A town had a minor bounty for the extermination of a den of kobolds, say 500 gold.  Yet that bounty has been reposted time and time again, increasing each time, as adventurers take it only to never return.  Now it's gotten up to an amount of gold best described as "interesting".  The villain?  A regular kobold, but an absolute MASTER of traps.  His den has been fitted with more deadly traps than you could shake a fist at.  This provides great opportunities as well for the whole "notes on corpses" lore building if you're into that thing (I am), and a chance to flex your puzzle building muscles.  Be sure to throw a few clever twists in there too- such as, the doors have very simple puzzles or riddles indicating the correct path, but the "correct" solutions are all trapped and the untrapped path is the one which is offset one to the left or right of the riddle's solution.

- A town has been having many of its residents performing strange and / or terrible acts, and then once imprisoned swearing up and down they didn't do it, despite being caught red handed.  Several high ranking officials even have been suddenly turning on those closest to them or performing acts totally out of character, and they swear there must be some other force at work.  The villain?  A necromancer who has seized control over the ghosts which inhabit the graveyard, and is using them to possess people while they sleep.  His motivation?  Pure chaos, a worship of a chaos deity which makes him want to cause as much mayhem, destruction, and sorrow as possible.

- The party has been having an image problem.  EVERYWHERE they go, their name is just getting dragged through the mud.  People they interact with get robbed, assaulted, or worse, and whenever there are witnesses, they swear it was a member of the party.  They can subsequently prove their innocence, but it's beginning to get on their nerves.  The villain?  Their mount!  A Doppleganger Druid has been posing as one of their horses (or if they don't have mounts just following them around as an animal) and then posing as them and causing mischief in their wake.  Apparently they messed up some plans the Doppleganger had, like WAY back, and this thing just doesn't know how to let it go.

- The party was sent to retrieve an item from some ruin.  It wasn't that big of a deal.  There was this annoying snake thing that put up a pretty good fight, but they beat it, retrieved the item, and washed their hands of the affair.  Didn't they?  The villain?  The spirit naga!  This can be uncorked after pretty much any dungeon, the thing just won't die, no matter how many times they kill it, and it seems hellbent on chasing after them as soon as it comes back and attacking them again, and again, and again.  Ultimately they'll have to do *something* other than just kill it, whether that's trapping it or whatever, and that's easier said than done with a creature with dimension door and the ability to dominate any prospective captors.  Note:  This does require giving it some means of tracking the party, whether that's a scrying spell or whatever.  Still, if you want something the party will come to LOVE to hate, this is the one right here.

There's 5, hope that's helpful!

As players progress in level their exploits should become more widely known. Reputation is important in campaigns for me, especially where the players are acting in places with large populations.

So one minor villain in a town was a politician, Mayor Weskit. In my campaign he was bitter because the party had removed one of his major sources of funding while rooting out a cult in another town. He'd spread some nasty rumors about them in his town, and the entire town was somewhat hostile. It made checks harder, items more expensive. I made it clear there was Something Up so that the party didn't just think I was making things difficult for them without reason. The mayor was perfectly civil to their faces, even going so far as asking them to dispatch of some small threat nearby, but the "threat nearby" was a peaceful group of lizardfolk who had built a home next to a waterfall. His plan was to set the party up as indiscriminate brigands, jail them, and find new support from the town and a rich enemy the party had made. 

This isn't my Best Villain by far, but my best villain is a dragon/Mystic big bad, so you get Mayor Weskit--a small annoyance who brought on a fair amount of good roleplay and helped the party lean back from jumping straight to battle without all the details.

One of my favorite villains never even made a physical appearance in game.

A player I had decided to make a over the top hack and slash fighter. He was what you would figure lots of str, dex, con, and the lowest cha available. Had no family all killed said his background. Love to call himself the God of war.

My "villian" was in fact his twin brother, that was just like him named Tarben. When the player would enter a new village Tarben had been there and the local guards were looking for him, and of course saw the pc. Next town oh look the local thieves guild is looking for Tarben cause he owes them gold, and of course find the pc. It got to a point the pc was actively trying to find this "imposter", but was always a step behind.

The player loved it, and it gave me quick easy hooks, and him fun role play. Not a traditional villian but the hell he caused the pcs was priceless. 

A current villain in my own setting is one of the character's father. 

This specific character is a Lizardfolk barbarian, and has warlock-like interactions with his totem spirit. He had the ability since birth to spit poison, which was seen as horrible witch-craft to the tribe he grew up in. For a bit of context, this specific tribe of Lizardfolk resides in the shadowfell, and have necrotic abilities. To anyone else, this character would have not have been anything special.

The villain is vulnerable to poison and acid. He is terrified of his son, though he is too tough to admit it. Cantch'm'ntar is the villain's name. He has a magical belt that lets him draw blood out from another creature and take one ability from that creature. Except if that creature has acid or poison in its blood. I love role playing this villain as he is actually terrified on the inside, even though he is a tough chieftain to his people whenever he is in public. I use him to creep out the party, or flat-out terrify them, which is always fun.

I know he sound over powered-and he is-but its still soooooo much fun to use him.

I like making villains designed round the players. So looking at their backstories and how a PC acts I will then make a villain who would get their attention or hit home the most. 

This has resulted in my current campaign of a Oni Warlord who prefers to slowly destroy aspects of a person's life rather than killing them out right. As death is a simple and quick end. But destroying a person's way and thinking and morals? Now that pain can last for a long time. His stats are a modified Oni so he has a few extra abilities. All of which are chosen with his way of thinking. He has Command so he can make noble types shamefully beg for their lives (like the parties Paladin). Then he will do certain things in fights to mess with people. For example even though it made the encounter more difficult for him he purposely ignored the party Cleric. As she followed Helm and was all about protection. So he purposely beat the crap out of the party and left her undamaged to prove she is incapable of protecting anyone. 

I have more plans for him oh is he fun to play mwhahaha.

Honourable mention: One villain I used in a past campaign was literally Dio from Jojo's Bizarre adventure. Sadly we had to put the campaign on pause for reasons. But I really want to return it. As using Dio would be a WORLDO of fun.....

I will always support a rival party of some sort that shows up and harasses the players at the worst possible moments. In my campaign that just ended this week I had a rival party led by a guy named Janne. He and his party members showed up when the party was split, did a number on those that were there, and escaped when the other party members showed up. He and his party showed up about three of four more times over the course of the campaign, and the players hated him so much that they came up with "#JanneMustDie". Bonus points if you later decide to pull a rug out from under them and turn them into someone that's harder to hate.

Most of the best villains, from my experience, are the ones that gain exposure over multiple sessions. A villain that only is heard about during one session has a tendency to fade from mind as soon as you're done dealing with them. It doesn't mean necessarily that you have to always have a villain show up multiple times- they only need to be present once, but having a buildup, having the players hear about them and develop a sort of tension before meeting them, that (to me) always seems to be more effective than a one-and-done villain.

That said, my favorite one-and-done villain was a cambion that was always just out of reach of that spell or bow. Since I myself am a bit less of a rules-focused DM, I gave him the ability to use charm person from that aggravating distance. The party really wanted to kill him when he was finally in range, and they absolutely unloaded on him in what might be the greatest overkill I've ever seen.

I have a villain that my group gets angry just from hearing his voice. I can be with any of the group, grabbing lunch, getting a drink, heading to the gas station, just talking about the game to friends that don't play, and the moment his voice pops up the person in my group will just start to go on a rant.

The bad guy is created by the result of a tragedy, a presumed lost love. His love was a Dryad, the forest that was her home was cut down for homes and farmland. He learned the ways of the druid, thinking to bring her home back. Finding she was gone, that bringing the forest back was impossible, and angered at the loss of his love, he searched to teach the people of the world a lesson. I shall destroy civilization, I shall bring the peoples of this world back to a time where they needed and feared nature. He has taunted the players every time they stumble across his path. He has toyed with them, showing his power to be vastly superior to theirs, and then walking way like he's bored with his new toys. He has threatened them, if they continue to mess with his plans he will destroy them. 

He's made for a wonderful recurring villain, and he tugs at the moral implication of whether the players want to destroy him or rehabilitate him. This kind of villain requires knowing what tugs at your player's heart strings. You don't want them to immediately want to kill the guy, you need to make them sympathize with him even if they disagree with his acts. But once you make that connection, the players will love/hate that bad guy.

Quote from DMThac0 >>

I have a villain that my group gets angry just from hearing his voice. I can be with any of the group, grabbing lunch, getting a drink, heading to the gas station, just talking about the game to friends that don't play, and the moment his voice pops up the person in my group will just start to go on a rant.

The bad guy is created by the result of a tragedy, a presumed lost love. His love was a Dryad, the forest that was her home was cut down for homes and farmland. He learned the ways of the druid, thinking to bring her home back. Finding she was gone, that bringing the forest back was impossible, and angered at the loss of his love, he searched to teach the people of the world a lesson. I shall destroy civilization, I shall bring the peoples of this world back to a time where they needed and feared nature. He has taunted the players every time they stumble across his path. He has toyed with them, showing his power to be vastly superior to theirs, and then walking way like he's bored with his new toys. He has threatened them, if they continue to mess with his plans he will destroy them. 

He's made for a wonderful recurring villain, and he tugs at the moral implication of whether the players want to destroy him or rehabilitate him. This kind of villain requires knowing what tugs at your player's heart strings. You don't want them to immediately want to kill the guy, you need to make them sympathize with him even if they disagree with his acts. But once you make that connection, the players will love/hate that bad guy.

I usually go for the collector type. A person who always seem to seem to ge- who the party seem to get in his way in obtaining Evil artifacts for his own benefit. He keeps beating the party or tries to beat the party to get to the powerful stuff. Maybe a thief? or College of whispers bard. 

Basically a person who's flat out annoying.

I like to encourage the players to write villains into their backstory, which I use a lot. The Captain of the pirate crew that the sorcerer deserted was one of the best.

Within my Hoard of the Dragon's campiagn, I created a Green Dragon by the name of BIlephrax that scoffs at the idea of collecting paltry gold and treasure within her hoard. Instead, she likes to collect people of influence. She gathers as much information on people she deems worthy to be within her hoard until she can figure out the correct "currency" to subjugate them as one of her prizes / spies.

She then approaches them and forces them to become a spy for her. Depending on the person it could be gathering scandalous information on the person, or the implication of violence. When she finds someone she wants, however, it rarely ends with that person not being claimed as a "treasure" within her hoard.

This happened to one of my players. if Chromatic dragons are one thing, it is that they rarely cooperate with other Chromatic Dragons. Even with the "promise" of Tiamat being summoned within the Material Plane. As such, Bilephrax wanted nothing more than to make sure she lands on the "winning" side of the war between the Cult of the Dragon and the rest of the Sword Coast. So she began gathering spies on both sides of the conflict. That way when the time was right, she might be able to "pick" the correct side.

One of those spies, just so happened to be our poor Firbolg druid. He was selected by Bilephrax because his clan resided near one of Bilephrax's lairs. Knowing this, Bilephrax may have implied that if the Firbolg doesn't feed information to her then his fight to protect his clan from the Cult might be all for naught... Since she elegantly implied that she would turn his clan, and the entire forest surrounding his clan, into a sulfurous wasteland.

Needless to say he accepted her "offer" and now the party has an informant for a manipulative green dragon within their midst.

A Mind Flayer who actually didn't want to kill the player characters at all, he had no interest in outright killing people. He just wanted to awaken an ancient beast that I homebrewed that upon waking, doesn't stop until it eats an entire continent and gives birth to its offspring to begin the cycle anew, with the offspring upon hatching eaten the sleeping parent, and so on and so forth. He just wanted to wipe the continent clean and start over from a clean slate as he was disturbed at not only how people would constantly wage wars and leave ruin in the wake of their wars. The players had just gotten in the way of his task, and he decided that killing them was the best bet so he could get on with his goal of "resetting" the continent before all of the people came to live there.

He awoke the beast, which destroyed a good chunk of the continent but was plane-shifted elsewhere during its rampage which angered the Mind Flayer who Power Word Killed one of the PCs, but that PC had made a deal with a deity to be brought back upon his death, as a one time deal on the condition he'd serve for the rest of his days onboard this ship that sailed the ocean, captained by a goblin who had taken on the curse of the Flying Dutchman and had become Davy Jones. This PC arrived back on the spot where he was disintegrated and much to the Mind Flayer's dismay and shock, caved his head in with a flurry of blows.

As the Mind Flayer hit the ground dead, the Monk was allowed his goodbyes and now serves for the rest of eternity onboard that ship.

I once made a human bad guy who I don't quite remember the name of. It doesn't matter anyway. He was the leader of a cult that wanted to bring the two superpowers of my world: Freeland and Utopia to war. But as this was kind of a comedy campaign, he didn't make as much as a dent in the tension between the two factions, and instead only managed to anger the players by killing their family and loved ones. His motivation was that he got bored in this world of peace and over the top happiness and good. So, as any psychopathic madman, he said: "Hey, you know what this place needs? War!" So, yeah, that's the villain I don't remember the name of. He was pretty great, and had a cool boss fight. Hope this helped :D