Anti-Cosmo

Anti-Cosmo is Cosmo's evil anti-fairy counterpart. He wants to take over Fairy World, and for Timmy to be his godson. Cosmo and Anti-Cosmo are opposites, so since Cosmo is stupid but loveable, Anti-Cosmo is smart and evil. His wife is Anti-Wanda which is the anti-fairy counterpart of Wanda who is Cosmo's wife. Anti-Cosmo also has a son named Foop. Anti-Cosmo is voiced by Daran Norris.

Reference
Anti-Cosmo at the Fairly Odd Parents Wiki.