How to create scary villians that have good and convincing motives

I know this sounds really boring off the bat but I've found a really good way is just to take villains from other campaigns or even other games or media entirely like films. It's pretty easy to re-skin them, just add the flavour you're looking for to a ready made stat block of a creature/being that fits the general vibe of your villain. For example if you wanted to make a Sith Lord, I'd make a human variant with Sentinel feat, take Polearm Master at level 4 instead of an ASI, give him a sun blade with radiant damage and spells like Push, Hold Person and Call Lightning.

Maybe you want to make a villain that's like Batman, so gloomstalker ranger with one of the rogue subclasses would be great.

If you want to make it memorable, make it cinematic. Epic in scale and with steep consequences and exciting rewards. And as the DM, you're running the game. Don't be afraid to bend the rules a little bit to freak out your players every now and then. Give your villain a secret ability that you can unveil at a pivotal moment; just when the party think they're about to win and defeat the BBEG, BOOM, villain was secretly a weretiger the whole time and now players have fight a full health spellcasting tiger. Be careful with this though; for every time you mess with them, you want to reward them too.

In regards to motives, look at real world villains. Why did they do what they did? What happened to them in their lives that made them so evil? 

Good villains evoke an emotional response from the players, and when they deal with that villain, they have strong emotions about them.

This can't be dictated -- it is a metagame thing, not something they role play in a real sense. That is, while you can say that they make you feel very uneasy, unless the way the villain behaves or acts or things they do make the player feel uneasy, it won't really work.

Good villains inspire the most wild and nutso things player's can think of. With wild and nutso being something entirely dependent on your players. IF they are the type that charges, then a good villain will inspire them to wade through minions like unstoppable death dealers and fling fireballs and lightning bolts, and there will be leaps of rage and snarling attacks.

If they are the sort that gets creative, there may be a whole crazy series of things that they do to slowly wear the villain down, never really facing the antagonist until they have been whittled down to size.

Lastly, memorable villains challenge them and use the oldest tricks in the book. They will have a reason to do what they do that will seem ok -- it is that the way they do it that is awful. THere is no redemption offered. There is no mercy given. But they always speak to the emotions of the players, not the characters, even though the thing is key.

The easiest way is to take your time first to create an NPC that all the players love. And then watch that NPC die at the hands of the villain when the players cannot do anything to stop it.

Memory is always tied to emotion. Bring out the emotions that enable your players to make memories, and you will have a good villain who does so -- they need not have a bajillion hit points or a hundred special attacks (they can have the commoner stat block). 

Now, of course, a big part of this is the story as a whole. Does it have stages, does it follow the standard beats of a good story, does it have a rising plot that peaks in a climax and then has an after effect?

That helps guide those emotional beats, helps to build upon them.

That's how.

Make them more real than just "You open the door and see the BBEG".  I had a duo of recurring villian NPCs in my campaign. One left his name spelled in dead bodies on the floor of a cavern that the PCs were going to investigate, kidnapped some of the other NPCs close to the party and forced them to duel him, etc. Look at things your characters care about, storylines they are going to be involved in, places they inhabit and see how your NPC can do things that the PCs will take personally.

When I make a villain that I want to be super memorable I don’t sit down to make a villain. Instead I create a character who wants to accomplish something noble, but they’re willing to go to villainous means to accomplish that goal. So, for example, a person who wants to overthrow a monarch that they have deemed to be corrupt or bad for some reason, but they’re willing to blow up a marketplace full of civilians or something if they think it will further that goal for some reason. Then I igive them a horrific plan that actually has a real likelihood of succeeding, but make it just complicated enough that the heroes have a few different opportunities to disrupt that plan somehow.

Between the villain’s relatable nature and understandable goals, and their brutal and inhuman yet utterly ingenious plan, I find that’s a great recipe for a memorable villain.

What makes a good villain is where they live.  That is, the dungeon.  You need a good dungeon to go with your villain or they won’t be memorable in any way. You see, the dungeon is what makes or breaks a game of dungeons and dragons.  It doesn’t have to be a dragon at the end of the dungeon, dragon is just a catch-all for the villain.  So work on you dungeon making skills.  Also, what can be gained from confronting the villain is also what makes them memorable.  That is, the treasure.  Players don’t care much for anything other than finding treasure, that is the bottle line motivation of a D&D character. 

Case in point- Halaster Blackcloak, the Mad Mage.  He is the greatest villain in D&D history because he has the best dungeon. 

If you do a search on Youtube for How to create a good villain you'll come up with a bunch of videos to give you ideas. 

The main thing to remember is that a villain is the hero of their own story. 

DMs lair has an awesome series on making good villains, awesome boss fights with them, and intentions. Some of the things I do as a writer to make villains, is do this when planning;

Whats the villains powers and make stat block. (Typical, but helpful)  Add a unique cool feature to use in combat ex: Critical role’s laughing hand. Lower hp, louder the laughter is, and dangerous for the party

i also add legendary actions and a few legendary resistance so hold person won’t kill them

Then to make them more human, relatable memorable, make them have motivations and handicaps. 
motivation: villain wants to kill certain person

ex: their people/followers are threatened by them, or because they want to exact vengeance.

handicaps are things the villain can’t or won’t do. 
ex: villain is weakened in the presence of a lot candle, or the villain will not let any harm come to their family. It could be they will not leave their home country by choice or fear. 

It’s things like this that complicate the villain that in my mind make villains memorable. A villain should be threatening but also somewhat moral. Don’t get me wrong though, every single npc or villainous character does not need all this. Sometimes a psychopath murderer is just a psychopath murderer.

One option is to have the villain antagonise the party - whether intentionally or not. I have a villain who can reanimate the dead, and they come back with glowing blue eyes and cold in their limbs - Icelight Zombies, I call them. The party have encountered Giants with this light in their eyes, who have cold powers, and earlier were attacked by a troupe of goblins who they had already killed - and who were back from the dead. The goal was to tie the players story, even when not interacting with the villain, to the villain.

One good trick is to listen to the players talk about the game itself.

This works for more than villains who are compelling; absolutely listen to them talk about the various NPCs in your world and see who they think is nasty. Suddenly... they are nasty. The players feel rewarded for figuring it out and you, as the DM, get to enhance their ideas for nefarious purposes.

Personally, it all comes down to motives for me. I don't introduce a cultist as "This guy is evil", I think of reasons why he wants to be a cultist. I'll see if it makes sense, and then ask myself "how would I convince a reasonable person that this is a good idea?". I believe that all villains are heroes to certain people. Ther'es always logic in their decisions.

Quote from ThorukDuckSlayer >>

One option is to have the villain antagonise the party - whether intentionally or not. I have a villain who can reanimate the dead, and they come back with glowing blue eyes and cold in their limbs - Icelight Zombies, I call them. The party have encountered Giants with this light in their eyes, who have cold powers, and earlier were attacked by a troupe of goblins who they had already killed - and who were back from the dead. The goal was to tie the players story, even when not interacting with the villain, to the villain.

 I like this one.  They know someone is doing something, they know they killed those goblins, they may even figure it is a necromancer, but where is he? You can really amp this up by describing the way one of the NPCs was killed, so that the party will recognize it later...

The level of villain or antagonist is really the first question i'd have to ask.  Do you want them to be a final boss or a thorn in the side.

I tend to like weaving the small pond bad guys (the ones that are locally bad) into the story slowly and sometimes as someone the party perceived as good.  I had a person the party was rescuing from a curse (lycanthropy) and they heard rumors of an alchemist in the next city over.  I made his building look out of place and he asked for a couple of items that are common to potions (herbs) and then randomly an obsidian heart.  they went through with it without questioning it, and then when they failed to think through why he would accept an unpowered one for the brewing of said potion to cure or control her curse they just went with it.  Turns out he used it to exact revenge on a city that turned on his master and exiled him, leading to his death, and the Alchemist went and found a way to power the obsidian heart and use it to power a whole labyrinth in the sky to try, the party then met him on the top floor and the big reveal that he was never really good but simply waiting for his opportunity to exact revenge. 

While my story is a homebrew and an outlandish story, the point of going through it here is that it made the party feel a bit gullable, which has led to more insight checks and also an interest in hunting him down later.  a minor antagonist doesn't have to be someone that is bad to their core, it can instead be someone whos morals and values dont end up following the logic of the party, and leads to a meeting down the road where the go from on the same side to opposite sides.  This is also one of many ways that i've introduced bad guys.  I've had the party walk back to town and witness an event, i've had world events that seem out of place for the area they are in, so it's really about just being creative and finding ways to connect the party to these situations in some way so they can feel it necessary to want to pursue this person and find out why at minimum and maybe end them in the worst of situations.

I don't know about scary, but a memorable villain has multiple encounters with the party.  Ideally, he does things that make your players mad and want to kill him.  Are they financially motivated?  He steals all their gold.  Like gear?  He sends monsters that destroy their prized magical item.  Emotionally invested in an NPC?  He kills the NPC or worse, turns them against the party in some way.  Maybe he ruins their reputation in an important organization (eg army, causing them to be court marshalled).  

The point is after several encounters with the villain or the problems the villain creates, the party absolutely loathes him.  A tough enemy, or an enemy with tough henchman or a cool castle, does not hold the sway of someone who has tormented your players and made them miserable.  

The villain should have a Master Plan, and should be enacting the steps of their Master Plan in order to achieve The Thing. Each step of the plan should effect the world in some way. The villain is building an army of orcs crossed with goblins? They need resources to do so and start raiding villages and cutting down large swaths is the neighboring forest, so when the players come across the forest guardians, they hear and see how the villain's Plan is affecting the world. Players continue to see more and more examples of the BBEG's villainy and, even if they've never met them directly, they gain an understanding of the villain's character and a drive to work against them. 

How the villain goes about their plan also tells you a lot about them too. In the above example with my thinly veiled Saruman bbeg, his actions betray a character that does not care for things that grow, has a "mind of metal", will burn the world in the fires of industry to bring what he calls 'order'. How they do it is equally important to what they're doing if you want your players to get a sense of who they're dealing with. Are they methodical? Brutal? Sympathetic? Monstrous? Mad? Vengeful? Factor these into how they interact with the world and what changes they bring about in it, and your players will feel more of that connection to them and when they finally meet the villain in person, it'll be properly set up in their minds. 

Make your BBEG sympathetic. No one wakes up evil. Everyone thinks they are doing God's work. Our errors are where evil creeps in. Villains who are "noble" at heart but broken, crazy, or ruthless, can be sympathetic when the cause seems just, but the actions to them are horrifying.

Quote from PheanVindex >>

Make your BBEG sympathetic. No one wakes up evil. Everyone thinks they are doing God's work. Our errors are where evil creeps in. Villains who are "noble" at heart but broken, crazy, or ruthless, can be sympathetic when the cause seems just, but the actions to them are horrifying.

 I disagree that a villain HAS to be sympathetic. Many memorable villains aren't. Emperor Palpatine doesn't need a tragic backstory to be compelling, he just needs do be exactly what he is. I don't need to sympathize with Professor Moriarty in order to be compelled by his formidable intellect and find him a worthy rival/foil to the hero. 

You definitely can make sympathetic villains, but sometimes equally fun is the one you can hate with no reservations and want to unambiguously take DOWN.

Quote from CharlesThePlant >>

Quote from PheanVindex >>

Make your BBEG sympathetic. No one wakes up evil. Everyone thinks they are doing God's work. Our errors are where evil creeps in. Villains who are "noble" at heart but broken, crazy, or ruthless, can be sympathetic when the cause seems just, but the actions to them are horrifying.

 I disagree that a villain HAS to be sympathetic. Many memorable villains aren't. Emperor Palpatine doesn't need a tragic backstory to be compelling, he just needs do be exactly what he is. I don't need to sympathize with Professor Moriarty in order to be compelled by his formidable intellect and find him a worthy rival/foil to the hero. 

You definitely can make sympathetic villains, but sometimes equally fun is the one you can hate with no reservations and want to unambiguously take DOWN.

Yeah, imo it's best to have multiple types of Evil characters.  Have the one that is all for their own ideals of a society and they'll go through whatever they think is best to change it and ignore anything else that it may impact, have one that's just out there to have a good time and their idea of a good time is to watch people suffer, and have a few that go back and forth on what side they are on.  The party in the end kinda chooses to be sympathetic on their own, so i'd focus mostly on having a good mix of characters opposite your PC's, it keeps it more fresh than every one of the opponents being the same repetitive type of BBEG.

Quote from Arek_the_Cleric >>

How to create scary villians that have good and convincing motives

That's the key point - make their motives good.

Consider Thanos from the Marvel movies. What was his motivation? Overpopulation and food shortage.Those are worthy goals. What made him a villain was his method. As an aside, his method was also stupid - sure, he killed half the population but he also killed half all the animals and plants, in other words half the population now have half the food source, making no difference to food shortages.

1st make likable npc, stray friendly dog anything the players are likely to keep returning to, have the NPC ask for minor help and reward the players, and give discounts or special access to things.

then when the players are off adventuring have something bad happen to them, (kidnap, destroy business, kill family members) but not kill the fav NPC, now they will want revenge. 

The closer they get to the villain the more destruction they uncover. This is a good time to find the fav dog that ran off sacrificed itself to save NPC… 

NEVER EVER let them encounter the Villain until you are read to fight… have several ways out for the villain as to not TPK the party early

when they finally get to kill them, have them find out this villain is one of many under the command of something much greater… Even have another villain steal kill the villain this will transfer all the rage to the new villain. 

Repeat , add more loveable npc, cause more chaos