Hard to decide which characters have been my favorites, but the one that's gotten the most positive feedback from other players (I've had folks ask me to play him in their campaigns based on the war stories I've told) is
Ripper, the halfling thief.
Back in college, I wandered into the cafeteria to find some folks playing a game - it was the old module where the Circle of Eight have all disappeared or been murdered or something like that and the party are supposed to be their underlings trying to find out what happened (or however that went). Anyway, they offered to let me jump in, and I got handed a pregen halfling thief with a pretty serious magic dagger and a
ring of jumping. I forget what the character's name was.
I think the DM had modified the adventure a bit, because at one point we ended up trapped in a burning tavern with a bunch of robed and hooded guys outside trying to keep us from escaping. There were a handful of the guys in the tavern with us (yeah, their buddies were perfectly okay with sacrificing them to get us...), and I managed to backstab a couple of them by crawling under the tables and getting behind them. (The DM was pretty lenient with the backstab rules.) Then I got up onto a table and used the
ring of jumping to land on some guy's back halfway across the room. The Dm ruled that a halfling flying more than twenty feet across a room to land on your back and try to slice your throat counts as a viable backstab, lol.
Despite thieves being crap in combat back in the 1e/2e days, I managed to take out a small handful of them by myself. When the last few guys inside were getting wiped up by the rest of the party, I grabbed some of the torches they'd tossed in through the widows and tossed them back out.
But we were still going to end up toasted since we couldn't get out and the walls were on fire.
So I did something that shocked the entire table.
I launched myself out through one of the windows and charged the guys out in the street, screaming like a demonically-possessed badger. I'd already tossed some burning oil out the windows at the start of the fight, and used the
ring of jumping to constantly switch positions, leaping back and forth over the oil so they couldn't gang up on me. I was bouncing around like Belkar from OOTS, screaming and taunting everyone and trying to get them to come after me. One of the party's fighters had followed me out the window, convinced I was going to get myself killed. Between the two of us, we managed to clear out enough space to let the rest of the party fight their way out.
For the rest of that adventure, I played that halfling thief completely against type, doing all sorts of outrageous things that people weren't expecting. The jumping backstab became my trademark move.
When I got into a 2E game later on and managed to roll both high Str and max Dex (as well as a fairly high Int) on my character, I decided to resurrect the halfling...
He was now
Ripper, the halfling fighter/thief - the largest halfling anyone had ever seen, muscled like a pro wrestler, and often mistaken for a small dwarf at a distance.
He had huge muttonchops and a personality three times his size. He was a charming ladies' man, he drank and swore like a dwarf, he had no problem picking a fight with anyone, and he'd often pass the time singing Orcish drinking songs to the tune of Elvish love ballads and Elven love ballads to the tune of Orcish drinking songs at the top of his lungs. He wrote poetry and spoke six languages. He was also a clever and devious bastard.
I found him a
ring of jumping and some magic daggers as quickly as I could, and making a flying leap onto a target's back, wrapping his legs around their chest to hold on and cutting their throat with dual-wielded daggers was his signature move.
Rather amusingly, however, one of his first magic items was a set of
gauntlets of ogre power...

People would stare at the sight of a halfling walking down the street with a bastard sword slung over his shoulder, and bristling with daggers all over. There weren't any weapon restrictions on backstabbing back then and because he had to wield it two-handed since he was small he did some
serious damage with it.
Whenever I played him from then on, I always made sure to acquire his
ring and
gauntlets as soon as I could, and always armed him with a ton of daggers and that bastard sword. (Sometimes the DMs I played under would just up and give me those items just to see Ripper in full effect). In one 3.5 game he was fighting an ogre once when I got annoyed at some bad dice rolls. So he dropped the bastard sword and started punching the ogre in the kneecaps until it fell over, then stood on its chest and proceeded to pimpslap it to death. In another, he used the ring to jump off the walkway of a high castle wall, sailing out into midair several stories up and using the momentum to land on a distant guard below.
Ripper is basically an in-game manifestation of my id, with almost no superego to overrule his impulses. When I play him, I'm constantly looking for opportunities to let his personality, flair and cleverness generate entertainment for the rest of the party and set up opportunities for them to step into the spotlight.