Susan Margaret Collins (born December 7, 1952, in Caribou, Maine) is the junior U.S. Senator from Maine and a member of the Republican Party. Collins was re-elected on November 4, 2008.

Collins is a Phi Beta Kappa graduate of St. Lawrence University. She worked for Senator William Cohen from 1975 until 1987, when she became chair of the Maine commission on financial regulation. She served in this position until 1992, when she briefly served as New England regional director of the Small Business Administration. She was the Republican candidate in the Maine gubernatorial election of 1994, but both she and the Democratic candidate, former Governor Joe Brennan, were defeated by the Independent candidate, Angus King.

In 1996, when Senator William Cohen announced his retirement, Collins announced her Senate candidacy. After a difficult three-way primary, she defeated Democrat Joe Brennan in the general election with 49% of the vote to Brennan's 44%. She was reelected in 2002 over State Senator Chellie Pingree (D), 58%-42%, and again in 2008 over Rep. Tom Allen (D), 61.5%-38.5%.