As the title suggests, what are some of your favorite NPCs you've created? Where did the inspiration for that NPC come from?

My personal favorite right now is Harry Hoblin the Happy Goblin. He's a Goblin Bard with his own theme song that roams the countryside with his trusty tiny lute (ukulele), singing songs, looting, pillaging, and eating puppies. The inspiration for Harry actually came from a piece of misaddressed mail I received, and I thought, hey, that'd be a funny goblin. My wife and I sing the Harry Hoblin song all the time around the house.

Our favourite so far was "dangerous" Bob, the very deadly friendly NPC who was great enough to later become a main character. 

We've also had Frank, the proprietor of the Gargantuan Golden Dragon (inn) and Clint, the owner of Citizen Arcane (a shop of miscellany.) Dammit the beholder thought everyone was his master, and was very chatty. He was popular.

I'm hoping werebear bartender will amuse, and have pixie Lawman to introduce.

Emrys Timestrider, my own personal take on Merlin. He was a side character, someone the PCs knew of but didn't know directly, for a very long time. He was called timestrider because nobody could remember a time when he wasn't around, and wasn't ridiculously old. Even old guys were like, "that guy looked 70 when I was 15." He was a tiefling (though in this particular world they weren't so obvious, they could pass as human to most, and only a few knew his true background) druid/sorcerer. I did my best to play him as seeming somewhat lawful evil even though he was chaotic good, just to keep him mysterious and unpredictable.

Also, he was the world's only level 8 character in an E6 campaign.

My favorite to roleplay for the group was Thomas Wadsworth. An aristocratic hill giant (think 19th century British colonialist) that was only rampaging because everyone had forgotten his birthday. Inspiration was my dad. 

Players favorite was a toss up between a bluebird they were trying to get information out of about the whereabouts of their squire using beast speech (he taunted them relentlessly and threatened them in a Goodfellas gangster style voice)  and a bard named Fillmore McCracken that had a knack for sexual innuendo. He had no shame and tried to put some serious moves on the Lizardfolk Barbarian . Inspiration, the bartender at a gay club I used to Dj at. 

My favorites are always the ones that the players end up talking about later. I had just a run of the mill encounter with an Ettin, which was arguing with itself over how to open a puzzle box. I had barely fleshed out that "character" at all, but the PC's loved it. 

As for my personal favorite, that's gotta be Lady Marie, the feisty young War Cleric who wants nothing more to be an adventurer, if it weren't for the fact that she's in training to become the next leader of the temple she's at

I look at what the NPCs does in the world.

Then I try and think what actor/actress I would want to play them if this was a movie. That gives me a bit of a physical / behavioral template to start with.

Add in what they want - what are their motivations?

Then I vary around physical and behavioral traits a bit, add in 1 or 2 stand-out characteristics, and see what develops organically from the NPC/Player interactions.

That might sound a bit complicated, but I find that with practice I can jot down notes on the fly, even for "surprise" NPCs: Aceton Costas; Exarch of Coria; Played by Mark Addy; Broad stance, confident, no nonsense; behavioral tick: smacks leather riding gloves into palm for emphasis ( in this scene ); Verbal tick: Hmmmph!; Wants: to keep the incident quiet, get intelligence on the Aisu; Will: accept the party as agents if suggested.

I don't have that much detail for "shopkeeps" and other throwaway NPCs - typically I'll just pull a variant of some stereotypical stock appearance / behavior - although it's occasionally fun to go "all in" with those as well; keep the party from getting too complacent.

The one I've liked best in the current campaign is probably Elmar Rieger, ranger and scout for the Highguard, seconded to the party as a military guide for their expedition into the Rala Gap. Blond, good looking, not at all modest about it, slight German accent ( badly done by me ), jovial, easy going, talkative, tends to talk about himself in 3rd person, friendly rivalry with some of the party members ( Oy ... you fight like farmers ... ).

He's also the NPC that gets brought up spontaneously by the players - so I'm happy about that :)

My favorite so far is Ariel DuBois, a Robin Hood-type character (a fighter of the Arcane Archer school, in technical terms) that has vaguely parallel goals to the PCs. She's a half-elf, but I wanted to buck some of the stereotypes about elves/half-elves - so she's incredibly tall and muscular, and she has more heart than sense, to put it delicately. She is very compassionate and cares a lot about helping people, but she rarely thinks through the full consequences of her actions, which leads to her making some pretty stupid decisions - like when she attacked the party in a case of mistaken identity. (Quite the first impression, that was.) Even worse, she has the Charisma to convince people that her stupid plans are actually good plans. (She thinks they are!) Her girlfriend, a much more level-headed rogue, is basically the only reason she's still alive.

Aerik - Barkeep at the Boar's Head Inn. Always sounds annoyed, always polishing a mug, and seems to know the right information at the right time. He's got stories for days and was interesting enough I was forced to make him a PC in my fiancee's game.

Tic and Tak - gnome siblings who are nothing short of a disaster on legs. high pitched nasally voices and talk way too fast. They're the bane of the entire party when they show up because the group knows something is about to go horribly wrong.

Warren - Halfling bartender, he is like Tom Cruise from Cocktail mixed with a used car salesman and a game show announcer. He's charismatic, bouncy and has a way with words. The party loves to stop by his place just to hear me play him up.

Gazmon - Dragonborn Druid. He's a big bad, but I've played him as this over ambitious, taunting and arrogant person so well that just the sound of his bad Indigo Montoya voice will make my players want to murder something.

Of all the NPCs that have given me renown in my D&D games though, it's Meepo. Every single group that has ever done Sunless Citadel with me falls in love with the way that I portray this little kobold. I have players from games I ran decades ago still talking about it, I have long time players who'll replay Sunless just to have more time with Meepo, and I have players who will bring new players to me specifically so they can learn the game through my rendition of Sunless Citadel and the interaction with Meepo.

My personal favorite NPC is Brentlyn Torwinter, a tiny halfling bard who roams the world walking on stilts and playing the otamatone and the kazoo. I made her after I listened to one specific Demi Lovato song on repeat for a week. She used to have a sad backstory but after I gave her the kazoo that all fell apart. 

For my players the favorite is probably Jeffreyson Albersworthen, who takes different forms in every campaign but always has the same name and the same job: census tracker for the gods. I got the idea for him after I got a cold, took ridiculous amounts of drowsy cold medicine, and decided to do my Government Studies homework. He appears, usually after a really bloody battle, and demands to know Exactly How Many People Were Killed Please And Thank You. It kills my players with laughter whenever I bring him out, especially since I'm still not good at accents and the guy is stereo-typically British.

My personal favorite, and I have a feeling my player's personal favorite NPC is Tonk, the goblin. He was a filler NPC for a tavern that the group quickly took a liking to. So I kept building backstory for him while playing and now I've gone so far as to play him in a PbP on the forums here from when he was younger to breath more life into him. Now days, he is literally an insane goblin pirate who lives in what is essentially the underdark. The group is in a very large city that has begun expanding the city deep below the current city, in old mines. He thinks everyone is a goblin no matter their height and he owns a giant ship with the trademark black mast w/ a giant green goblinoid face with an eye patch over his right eye. There is an underground lake butting against this underground city that he sails on. It might as well be an underground sea. There are also spots that will transfer a ship through different planes when events line up just right, and Tonk knows of these events. They ran into him two sessions ago when they needed shelter for the night. They then spent the next 5hr session the following week trying to find more info about Tonk, completely putting their previous search on hiatus. They learned quite a bit about him, including that he owns the giant ship currently docked. They heard crazy stories about him, from other people whether they are true or not, who knows.

They found him two weeks ago, we play once a week. Tomorrow will be the third session since they met him and they've been talking about him every day since the end of that first encounter.

My current favorite, and he always gets a cheer from the party is Pete, the gnome who is also the proprietor of Pete's Potions, talks in a high pitched nasally voice but the fun part is his prices are never the same day to day or even person to person, he will gouge one party member then sell dirt cheap to the next, all based on interactions with him. Or sometimes it seems for no reason at all. 

Your NPC's are so cool. My favorite so far is Pual the gentle. A simple guard that joined my characters at the beginning of the campaign to prove that the Captain of our ship planned a werewolf attack against the City. He looks at all children with kindness but sorry as if he has lost his own and refuses to lose another child to the darkness of this world. (Or the Captain)

Pilchard Cantilever, evil gnome artificer, happily sent his nephews off to probable death to protect his profit margin. Now minus a toe following a prolonged encounter with the players, and plotting revenge.

One of my favorites (and my players’ favorites) was Cade Hardbrooke. He’s a human gunslinger. He was essentially a fantasy version of a cowboy (accent and all). He left the party somewhat recently, and hasn’t been seen since. 

I take my name from one of my favorite Non Player Characters.  Geann was a Ranger, one who didn't talk much.  I put Geann in the game so my players could get advice when they needed it, and made Geann very taciturn so the players wouldn't expect to hear from their Ranger guide much.  Geann would park under a tree, put a hat over their eyes, and pretend to be asleep.

Another favorite was named "Food".  The party was in desperate need of a warrior type, and they spotted this huge hulk of a man pulling a plow along behind himself.  They purchased him outright from the local farmer and put a sword in Food's hand.  Food had the intelligence of a can of catfood, so he didn't get the idea at first.  They tried to show him by moving his arm around in swinging motions with the sword, but he remained a hazard to the players and himself more than to any enemy they might face.  In the end, they taught him by giving him something good to eat, pointing at something, and shouting "Food" at the top of their lungs while pushing him at the target.  Food would bash away with that sword, eager for something to eat, and come back.  I guess the enemies he killed didn't taste so good.

There was also Goreshtag the Barbarian.  He was huge, very loud, and had an outrageous accent.  He'd tag along behind the party singing in that voice of his, with "Veer on a schekrit mieeshun..."  In something that sounded vaguely like the Swedish Chef from the Muppets. 

My favorite so far is Mnemosyne, a white-and-orange sentient, talking cat.  She’s the caretaker of the party’s newly acquired estate, with a dry sense of humor and a tendency to passive-aggressively taunting the PCs with the fact that she knows more than they do about the tower, its history, and its contents.  They’re also starting to realize that she’s a lot more powerful than they first assumed, which has been a ton of fun for me, role playing her smugness and plausible deniability!

She and the other fifteen cats living in the tower are a race that I made up years ago (long before I had even heard of D&D), the Cheshire Cat race.  They are powerful fey, similar to the real-world Cat Sith of the Irish Sidhe, but with some added features such as Spider Climb, invisibility (their grins stay visible, of course!), illusion magic and spellcasting, power over dreams, and a love of riddles.  They are still cats, of course, so they have a rat made of smoky quartz to play with (it’s a homebrew Figurine of Wondrous Power), cat trees on every level of the tower, cat doors in the base of the tower which are protected by illusions, and more.

She’s been playing with the PCs for a couple of sessions now, as befits a cross between a faerie and a cat, but yesterday my players took their first long rest in the tower, and when they woke up, everyone was covered in sleepy cats!  It was a ton of fun role playing the characters’ attempts to get the cats off of themselves so that they could actually start their day!

Sam Baker: If you recognize this as one of my players you better skip this one. 

S'chatek Arvalir Ras'miir, aka Sar - A thri-kreen ranger/rogue that used to be their guide across a desert. For some reason, one of my player's druid trusts him completely. Even though literally stabbed him in the back. Twice. Plus, thri-kreen are just awesome.

Purity - A small tiefling child who was being assaulted by villagers when my players rescued her. She was meant to be just a side quest, but the Bard and Sorcerer love her and now want to adopt her.

Sordian Grey - He made the Rogue freak out, so he's definitely one of my favorite characters. Plus, he has a nice anti-hero vibe and looks awesome.

larry the bookshelf guy!! he is a human(?) who has a 'pet' tiger squeaky toy, which he thinks is real, he constantly brushes it using a toilet brush, and he only communicates using the word 'bookshelf,' of course the party hasnt figured out hes secretly a spy for the SWG(sogel wind guards, its the FBI)

Do bunnies count?