Zombozo.

Ah, yes. Zombozo the clown.

What a splendid idea these nutjob scientists had. "Let's take a psychotic, murdering clown's corpse, and experiment on him to see if it can be brought back to life!" A lovely idea indeed.

This sharp-toothed immortal serial killer has been terrorizing Bellwood for a while, in the mornings seen biting the heads off poodles for breakfast; at night, scaring children in their rooms so they'd run to their parents... only for them to find balloons under the covers, their family gone, forever.

The Plumbers fought the undying menace valiantly, even after the sacrifice of many good agents, and while the rest of his gang escaped, they finally managed to capture him. Now he waits, in his room. Messing  with anyone foolish enough to take a peek into his cell... amusing himself before it's once again time to unleash terror upon the city.

Sorry he had to be in the game,

Newman.