Anti-Cupid is the Anti-Fairy counterpart of Cupid. Not much is known about Anti-Cupid. He was only seen briefly among other fairies that were being sucked into the Hyper-Cube-Net in When Nerds Collide!
As Cupid deals with love, it is possible that Anti-Cupid deals with hate or ruining relationships. It is debatable if Cupid really has an opposite of himself since he's considered a god more than a fairy. Anti-Cupid was briefly seen in Will the Real Cosmo Please Stand Up?