Mark Robert Warner (born December 15, 1954) is an American politician and businessman, currently serving as the junior United States Senator from the Commonwealth of Virginia. He is a member of the Democratic Party. Warner was the 69th governor of Virginia from 2002 to 2006 and is the honorary chairman of the Forward Together PAC. Warner delivered the keynote address before the nation at the 2008 Democratic National Convention. Mark Warner's experience as a congressional staffer and Democratic Party fundraiser in the 1980s prompted his involvement in telecommunications venture capital; he founded the firm Columbia Capital.

In 2006 he was widely expected to pursue the Democratic nomination in the 2008 U.S. presidential elections; however, he announced in October 2006 that he would not run, citing a desire not to disrupt his family life. Warner was considered to be a potential vice presidential candidate, but upon receiving the Democratic nomination for the U.S. Senate, he announced that he "will not accept any other opportunity." He is expected to become the state's senior senator when Jim Webb retires from the Senate in January 2013.