Ivan Charles Messmer (July 23, 1931 – March 8, 2015) was a Canadian politician, who represented the riding of Boundary-Similkameen in the Legislative Assembly of British Columbia from 1986 to 1991 as a member of the Social Credit Party. He held several roles in the Executive Council of British Columbia during his term as an MLA, including and . He served alongside Jim Hewitt, and later Bill Barlee, in a multiple-member district. Following riding redistribution for the 1991 general election, Messmer ran in the new district of Okanagan-Penticton, but was defeated by Jim Beattie.