S
- Stacy Schiff, journalist, biographer, winner of the 2000 Pulitzer Prize for her biography of Vera Nabokov (graduated 1978)
- G. David Schine, entrepreneur, businessman, political activist
- Cory Schneider, Vancouver Canucks Backup Goaltender (graduated 2004)
- Peter Sellars, theatre director (graduated 1975); MacArthur Award (1983)
- Robert B. Semple, Jr., associate editor for the New York Times and a Pulitzer Prize winner for environmental editorial writing (graduated 1954)
- James Shannon, Former U.S. Representative for Massachusetts and former Massachusetts attorney general (graduated 1969)
- Duncan Sheik, musician (graduated 1988)
- Charles Monroe Sheldon, leader of the Social Gospel movement (graduated 1879)
- Peter P. Smith, assistant director-general for education at UNESCO and first president of the California State University, Monterey Bay. (graduated 1964)
- James Spader, actor (Class of 1978) (dropped out)
- Lyman Spitzer, physicist (graduated 1931)
- Benjamin Spock, pediatrician (graduated 1921)
- Frank Stella, painter (graduated 1954)
- Alexander Stille, journalist (graduated 1974)
- Henry Stimson, Secretary of State under President Hoover, Secretary of War under Presidents Taft, F. Roosevelt and Truman
- Richard K. Sutherland, U. S. Army general during World War II (graduated 1911)
- William Irvin Swoope, U.S. Congressman from Pennsylvania
Read more about this topic: List Of Phillips Academy Alumni