Brian David Mason is a Canadian politician who was leader of the Alberta New Democratic Party from 2004 to 2014 and served the Minister of Transportation in Rachel Notley's NDP government. He also served as the Government House Leader. Mason was first elected as a Member of the Legislative Assembly of Alberta for the now-defunct riding of Edmonton Highlands in a 2000 byelection. He was subsequently re-elected, and was elected in Edmonton-Highlands-Norwood after the riding was created in 2004. He chose not to seek re-election in 2019, and was succeeded by Janis Irwin. Mason was the longest serving NDP MLA in Alberta history, with a political career spanning more than 20 years.

The 2014 Alberta New Democratic Party leadership election was prompted by Brian Mason's announcement on April 29, 2014 that he was resigning as leader of the Alberta New Democratic Party after a decade in the position.