Slimer (also known as Onionhead and Little Spud) is fictional green ghost featured in the 1984 supernatural comedy movie Ghostbusters(as well as its 1989 sequel, Ghostbusters II), whose popularity soared from the subsequent spinoff animated television series The Real Ghostbusters. Slimer later starred in his own Slimer! cartoons when The Real Ghostbusters was extended to a one-hour format. Slimer also appeared as a representative of The Real Ghostbusters in the animated anti-drug television special, Cartoon All-Stars to the Rescue. Slimer was 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.
He is voiced by Frank Welker.