Sidney Green (born August 1, 1929) is a politician in Manitoba, Canada. He twice ran for the leadership of the New Democratic Party of Manitoba, served in the cabinet of Premier Edward Schreyer, and later formed the Progressive Party of Manitoba.
Green was born into a Jewish family in the mostly working-class north end of Winnipeg, Manitoba. He graduated from the University of Manitoba's Law School, and subsequently worked as a labour lawyer. While a student, Green articled with Joseph Zuken, then a Communist school trustee and later an alderman. Despite having some radical tendencies in his early years, Green never became involved with the Communist Party.
On the advice of Stephen Lewis and Lloyd Stinson, Green joined the federal New Democratic Party (NDP) in the early 1960s. He was the party's federal candidate for Winnipeg South in the 1962 election, placing a distant third in a riding that was acknowledged as unwinnable for the party. Shortly thereafter, Green won election to the municipal council of Winnipeg for a north-end riding, defeating Communist candidate William Kardash and John J. Thomas of the pro-business Metro Election Committee. Green was re-elected in 1964.
Green resigned his seat to contest Winnipeg South again at the federal level in the 1965 election. He became the first NDP or Cooperative Commonwealth Federation candidate to receive over 10,000 votes in the riding, but still placed third.