Holy Moses - Atilla, 1970.

Wikipedia does a pretty good job of summing this one up:

Attila was the name of a band featuring a young Billy Joel. Billy was a member of a band called The Hassles; he and the drummer, Jon Small, broke away from the Hassles and formed Attila in 1969. The instrumentation was mostly organ and drums, with Billy Joel also handling the bass lines with a keyboard, like the Doors' Ray Manzarek. Their creative partnership ended in 1970 when Joel allegedly ran off with Small's wife, Elizabeth,[1] although this did not end their collaborations, as Small produced Joel's концерт video as well as the "live at Shea stadium" performance

They released only one album, Attila, in 1970, later reissued by CBS Inc in 1985. Attila is often selected by critics and other music journalists as one of the worst rock albums of all time, but also receives a significant amount of praise from people who normally would not listen to Billy Joel. Joel himself has gone on record as describing the album as "psychedelic bullshit".[1]