James Roos Breithaupt KStJ CD QC (September 7, 1934 – August 29, 2018) was a Canadian politician. He served in the Legislative Assembly of Ontario from 1967 to 1984 as a member of the Liberal Party. He won a total of five elections, and was the longest serving former Member of Provincial Parliament (MPP) for Kitchener since Canadian Confederation in 1867.