Slimer

Slimer is a ghost made up of pure Ectoplasm and the first ghost successfully captured by the Ghostbusters. Slimer is well known for his gigantic appetite and the slime he leaves behind when he passes through solid objects.

Slimer is classified as a focused, Non-Terminal Repeating Phantasm, or a Class 5 Full Roaming Vapor. And a real nasty one at that.

Goin' Green
Slimer survived The Matrix in the opening round, and the Game Boy Screen in the second.