James Roos Breithaupt (popularly pronounced "bright-up"), KStJ, CD, OM(Pol), 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 is the longest serving former Member of Provincial Parliament (MPP) for Kitchener since Canadian Confederation in 1867.