Susan Margaret Collins (born December 7, 1952) is an American politician serving as the senior United States senator from Maine. A member of the Republican Party, she has held her seat since 1997 and is Maine's longest-serving senator.

Born in Caribou, Maine, Collins is a graduate of St. Lawrence University in Canton, New York. Beginning her career as a staff assistant for Senator William Cohen in 1975, she became staff director of the Oversight of Government Management Subcommittee of the Committee on Governmental Affairs (which later became the Committee on Homeland Security and Governmental Affairs) in 1981. Governor John R. McKernan Jr. then appointed her commissioner of the Maine Department of Professional and Financial Regulation in 1987. In 1992 President George H. W. Bush appointed her director of the Small Business Administration's regional office in Boston. Collins became a deputy state treasurer in the office of the Treasurer and Receiver-General of Massachusetts in 1993. After moving back to Maine in 1994, she became the Republican nominee for governor of Maine in the 1994 general election. She was the first female major-party nominee for the post, finishing third in a four-way race with 23% of the vote. After her bid for governor in 1994, she became the founding director of the Center for Family Business at Husson University in Bangor, Maine.