I think it'd be a better topic if it was: "A character I refuse to play again."
Because there's many characters I'll never play again. There is one in particular, that I doubt any DM would allow into his games--Ulrick Hammerstein.
First, he's an AD&D Second Edition Character. These days 2e seems to be over looked by many, though I'd like to play it again, where it not for the gripes about Thac0.
Second, he was rolled up using splatbooks and even some things out of the Skills and Powers line. (Hey, when I asked the DM, "What books can we use to roll up characters?" He said, "All of them."
Third, on top of this, Ulrick is the only character I've ever rolled an 18/00 strength.
Ulrick made it to 4th level. He could wield a bastard sword in each hand with optimized specialization and ambidexterity. All of his bonuses from specialization and strength easily overcame the penalties for using a bastard sword in each hand. To this day I maintain that Ulrick isn't a Drizzt clone, since Ulrick was human.
He was a weapon of mass destruction, getting something like 3-5 attacks every round. He would take the lead, armored up in platemail he'd bought with a gem he'd found in his first adventure. Often he'd kill monsters before the other PCs could get to hack at them. This annoyed the other players to no end, because the DM ruled that if you didn't participate in combat, you didn't get experience points. So if Ulrick stood at a doorway, and fought the monsters all by himself, he'd get all of the XP. (Not like that ever happened...)
The campaign Ulrick was in folded only after a few sessions because, in part, the other players where both annoyed and bored. I can't blame them. Playing a maxed out character was fun, at first, but it soon became boring, because combat wasn't a challenge. Low level monsters were just cannon fodder. But if the DM threw mid-level monsters at us, the group would be hurting (Ulrick would probably do okay though). So the campaign ended.