Joseph A. Day (born January 24, 1945) is a retired Canadian politician. He was a Canadian Senator from October 4, 2001 until January 24, 2020, and was the leader of the Senate Liberal Caucus from June 15, 2016, to November 14, 2019. He became the interim leader of the Progressive Senate Group on November 14, 2019, and served for slightly less than one month in the role. On the eve of his pending retirement from the Senate, Day tweeted his farewell remarks. He mentioned that it was an honour to serve his fellow New Brunswickers and all Canadians. Furthermore, he also gave a farewell speech. He retired from the Senate on January 24, 2020, upon reaching the mandatory retirement age of 75.