Robert Allen Nen (born November 28, 1969) is a former Major League Baseball right-handed relief pitcher. He spent most of his career as a closer. He is the son of former major league first baseman Dick Nen. He currently works in the Giants' front office as a special assistant to General Manager Brian Sabean.
Nen is best known for his years with the San Francisco Giants (1998–2002). He also played with the Texas Rangers (1993) and Florida Marlins (1993–97); in 1997, Nen won a World Series championship with the Marlins. After the 2002 season, Nen injured his throwing arm and has not played since.
Nen was known for an unusual delivery in which he tapped his toe on the ground before releasing the ball. His signature pitch, a slider, was nicknamed "The Terminator." It looked like a fastball until it broke straight down at the plate at a velocity of up to 92 mph. In addition to the slider, Nen had a fastball that reached the upper 90s. A splitter rounded out Nen's pitching arsenal.
Nen has 314 career saves with the Marlins (1993–1997; 108 saves) and Giants (1998–2002; 206 saves). He is 15th overall in career saves.