Simon Leendert De Jong (born 1942) is a former Canadian parliamentarian. He was first elected to the Canadian House of Commons in the 1979 federal election as an MP for the New Democratic Party from Saskatchewan. In 1989 he was a candidate in that year's NDP leadership convention to succeed Ed Broadbent finishing fourth. De Jong had agreed to be suited with a microphone in order to assist with a CBC documentary on the convention but forgot he was wearing it and inadvertently allowed back-room negotiations between himself and candidate Dave Barrett to be recorded in which De Jong agreed to support Dave Barrett in exchange for being named House Leader. More embarrassingly, a tearful telephone conversation with De Jong's mother was also broadcast.

De Jong remained an MP until 1997 when he decided not to run for re-election in that year's federal election.