Gray was elected to Parliament for the first time in 1962. He served the district of Windsor West for almost four decades, making him one of the longest serving MPs in Canadian history.
He was notorious for his stability as a politician.
He was "the Liberal Party's version of the Rock of Gibraltar," Don Boudria, a former Canadian politician, once said.
He served in several cabinet positions and was the deputy prime minister of Canada when he left Parliament in 2002.
“Throughout his career, Gray was guided by principles of social justice, good governance, sound democratic processes and programs that create opportunities for all,” the Liberal Party statement read.
He went on to spend eight years as the Canadian chair of the International Joint Commission of Canada and the United States. In 2008, he became Carleton University's tenth chancellor.
Gray was married to Sharon Sholzberg-Gray for 46 years. The couple had two children and eight grandchildren.
He was a Companion of the Order of Canada and received numerous accolades from universities, governments and community organizations including receiving the inaugural Laurier Leadership Award from the Liberal Party of Canada.