I don't know about a general name (Optimizer has a Z! Isn't that cool enough for you?), but here's some names for subsets that may come in handy:
OptoMiser: Really good at optimizing their own character, but won't help with anyone else's.
Fatal Optomizt: Makes "uber" characters with glaring weak spots (like a Berserker with a Will save of -1 at 20th level), and hopes the DM won't notice or take advantage of it.
Max/Miner: Works to make amazingly weak characters, and then says they're roleplaying better as a result.
Posergamer: Claims they have an godly character that could kill the whole rest of the group. Actually has no such thing - their character couldn't conquer a molehill.
Hunchkin: Munchkin who uses metagaming instead of raw character power. They've always got a "hunch" on which door to open (because they read the module).
Optic-Master: Can read the DM's notes off the reflection in his glasses (only works if the DM wears glasses).
Powerroller: Doesn't make that powerful a character, just rolls amazingly well, on everything. Are they cheating, really lucky, or psychic?