Wow, what a great topic for my virgin post on these boards... Since it's not limited to D&D, let's have some fun, but we'll start with the familiar.
Rakh! You have to yell/bark his name to get it just right. Kobold Warlock 2 with Cha 18 and Str 4. Unbelievably brutal, what with being small, fast, and able to run up walls and ceilings at will while flinging nasty purple lightning.
Uma: Fighter 2/Clr 1, a pretty enough young paladin-to-be who fell in a vat of potion of bull's strength as a wee toddler (ala Obelix). Not very bright at all, but loved animals and smiting evil, mmkay? Sort of a cheerleader to that campaign's goddess of war.
Hector Bellatortuga: Ars Magica Grog. Easily the most entertaining character I've ever played. A master of fanfare originally designed to be an amazingly minor character serving an elf knight. He wears a "magical" turtleshell hat that was given to him by a wizard. He thought it did just about any and everything, but it was completely mundane. Imagine Jeff Chaucer from Knight's Tale with a dollar of Antonio Banderas/William Shatner, all with bad fashion sense.
Plenty more after 33 years of RPGs, but they'll wait a bit. Someone else can have a turn.