From the "The Hardy Boys and Nancy Drew Meet Dracula" two part episode (09/11/1977 & 09/18/1977) of television series The Hardy Boys Mysteries.
Rock star played by real singer/songwriter Paul Williams. He's hosting a concert in Transylvania at Dracula's castle. he even sings "The Hell Of It" which he wrote for the 1974 fake band movie Phantom of the Paradise.
See also The Circus