Peter Sivess (September 23, 1913 – June 1, 2003) was a Major League Baseball pitcher. He pitched all or part of three seasons in the majors, from 1936 until 1938, for the Philadelphia Phillies.
After professional baseball, Sivess worked for a few years at Grumman Aircraft prior to joining the US Navy during World War II. Following the war, he worked for the CIA.
Sivess was raised in South River, New Jersey. He died on June 1, 2003, in Candler, North Carolina, aged 89.