David Hackett Souter (pronounced /ˈsuːtər/; born September 17, 1939) served as an Associate Justice of the Supreme Court of the United States from 1990 until his retirement from the Court on June 29, 2009. He filled the seat vacated by William J. Brennan, Jr.

Appointed by Republican President George H. W. Bush, Souter served on both the Rehnquist and current Roberts courts, and was often considered a member of the court's traditional liberal wing. In April 2009, Souter announced that he would be retiring at the end of the current Supreme Court term in June. On May 26, 2009, President Obama announced that he was nominating Judge Sonia Sotomayor to replace Justice Souter on the Court.

Souter was born in Melrose, Massachusetts, September 17, 1939. He is the only child of Joseph Alexander Souter (1904–1976) and Helen Adams Hackett Souter (1907–1995). After moving from Melrose at the age of 11, he spent most of his childhood and adolescence at his family's farm in Weare, New Hampshire. He attended Concord High School in New Hampshire.