Most OPed/Broken character(s) in VG history?

[Ostro]

Kirby in (original) Smash Bros. for me.
With people mentioning Meta Knight it looks like I have a lucky hand with Smash Bros. characters as I've picked Kirby from the very first minute without knowing he's crazy and Meta Knight on Brawl from the very first minute (I haven't played much of Brawl, though).