Jason Ryan Jennings (born July 17, 1978, in Dallas, Texas) is a Major League Baseball relief pitcher for the Texas Rangers.

Jennings attended Poteet High School in Mesquite, Texas, and was a standout in both football and baseball. In football, he won All-District honors at both, kicker and punter. In baseball, as a senior, he was named the District MVP and posted a .410 batting average, hit seven home runs, and pitched his way to a 10-3 record and a 0.92 ERA with 132 strikeouts.

After graduating from Poteet, he attended Baylor University where he played baseball from 1997-1999. Following his junior season at Baylor, Jennings was named by both Baseball America and Collegiate Baseball as the 1999 National Player of the Year. In what would be his final season at Baylor, he struck out 172 hitters in 146.2 innings and hit .382 with 17 homers and 68 RBIs. He also won his second consecutive Big 12 Player of the Year, consensus All-America honors, the Outstanding Player on the 1999 Big 12 All Tournament Team, and a spot on the 1999 All-Big 12 Academic First Team.