Jason Michael Grilli (born November 11, 1976, in Royal Oak, Michigan) is a Major League Baseball relief pitcher for the Texas Rangers organization.

Following his high school career at Baker High School in Baldwinsville, New York, Grilli was drafted in the 24th round of the 1994 Major League Baseball Draft by the New York Yankees, but chose not to sign. Instead, he opted to played college baseball at Seton Hall University, which he attended from 1995–1997. While at Seton Hall, Grilli once struck out 18 batters in a game to break Charles Nagy's Big East record. After a standout collegiate career, Grilli was drafted in the 1st round (4th overall) of the 1997 Major League Baseball Draft by the San Francisco Giants.

In 1999, Grilli was a key component of a midseason trade that brought Liván Hernández to the Giants, and sent Grilli and pitcher Nate Bump to the Florida Marlins.