Mighty Mouse - Andy Kaufman. Genius. Someone commented that it wasn't funny "out of context," meaning, without knowing Kaufman's comedy. But he was, at this time, totally unknown. SNL was a new show, and Kaufman was a new face. I remember watching, and laughing so hard, I loved this bit.
Andy Kaufman: My dad and I were already well aware of Andy Kaufman's "Foreign Man" act and his conga playing from his appearances on Dick Van Dyke's variety show. So it was no surprise when in July of 1977, I caught a rerun of Saturday Night Live where Andy transformed his foreign man character into Elvis Presley and brought the house down. He started to lose me with the wrestling stuff, but his Mighty Mouse bit is nothing short of unadulterated genius.