I got into D&D about two years ago. One of my favorite characters was "Captain Skalar the Scaleheart." He was the captain of our Pirates/Villains campaign, and He was so fun to play. I multiclassed as a Cavalier/Fighter, and gave him a ton of personality.
One quirk I gave him was that he would always begin a story with "Now listen up lads, this is my favorite story!" And/or he would end every story with "And that's me favorite story!" When he was finally confronted about it by the ship's navigator, my response was "Of course all the stories I tell are my favorite, they all have to do with Me!"
My favorite "good" character was an Entobian(bug person) Skald (Bard-Barian). His quirk was his introduction, which he would give anytime he met a new person:
"Hello, my name is Haldozan Herracross, world-class drummer and professional singer! Very skilled in Spells and Counter-Spells!"
By the time we finished the campaign, the entire party had memorized it and would sarcastically quote it right along with me without missing a beat.
I'm getting ready to actually GM for the first time, which will probably come in the summer. I'm going to run my friends through a home-brew Villains Campaign I've been making called "The Blood and The Water." The premise is this: A powerful country is secretly being run by a Vampire Mafia Family. The Family will have enlisted the help of the party to keep things in check at home and to keep tabs on the neighboring countries, as border disputes are becoming increasingly more common. One thing that I feel comfortable sharing here is a concept that I intend to implement: An Anti-party. Since my friends will be the villains this time around, I'm going to create a typical band of heroes to become recurring enemies and oppose them. More that that, I'm going to attempt to specifically tailor the Anti-party to counter the Party one a 1:1 basis. For instance: to counteract an assassin that uses invisibility, I'll employ a prestige class that grants blindsense and can dispel invisibility. To counteract a mage, I'll use a third party class I discovered that can sever magical abilities. I can't wait to try it out. I'll let you guys know how we all fare in the end.