Thelma Bessie Forbes (September 26, 1910 – January 5, 2012) was a politician in Manitoba, Canada. She was a Progressive Conservative member of the Legislative Assembly of Manitoba from 1959 to 1969, and served as a cabinet minister in the governments of Dufferin Roblin and Walter Weir. Forbes was the third woman ever elected to serve in the Manitoba legislature, the first woman to serve as speaker for the legislature and the first to serve in cabinet.
The daughter of Robert A. J. Brown and Annie Sheehan, she was born on a farm near Manitou, Manitoba, was educated at Manitou Collegiate and the Manitou Normal School, going on to teach school in south central Manitoba. In 1940, she married Edgar Forbes. They operated an Imperial Oil service station and an International Harvester dealership in Rathwell. From 1954 until the 1970s, they operated a farm in the same area.
Forbes was first elected to the Manitoba legislature in a by-election held on November 26, 1959,