Lydia Murdock is an American pop singer. She is best known for her answer song for Michael Jackson's, "Billie Jean", known as "Superstar", where she portrayed Billie Jean saying that she's "mad as hell" in the song's lyrics. The song was a hit in Canada and the United Kingdom in 1983.

In a November 1983 edition of the British music magazine, NME, it stated that "Superstar" was "the latest in a long line of replies destined to be forgotten".