Jason William Simontacchi (born November 13, 1973) is a pitching coordinator in the Kansas City Royals organization.

He pitched in the minors from 1996–1999 and from 2001–2004, in the organizations of the Kansas City Royals (1996-1997), Pittsburgh Pirates (1999), Minnesota Twins (2001), and St. Louis Cardinals (2002–2004), where he made his major league debut.

After transferring from De Anza College, Simontacchi attended San Jose State University in the 1994–95 school year and pledged the Cal Iota chapter of the Phi Delta Theta fraternity as a member of the Alpha Theta pledge class.

He also played in the Italian Professional League for Rimini Baseball Club and went 12–1 with a 1.17 ERA in 2000, where he played well enough to make the roster for Italy at the 2000 Sydney Olympics, where he was the winning pitcher against South Africa, pitched in relief versus USA and was the losing pitcher against the Netherlands, finishing the Olympics with a 1.17 ERA and 10 strikeouts in 15.1 innings.

Simontacchi suffered right shoulder problems from a torn labrum in 2004, and was released by the Cardinals at the end of the year.

He rehabbed in Triple-A, and when starters Jerome Williams and John Patterson both went on the 15-day disabled list in the span of 10 days, he was called up and started against the Milwaukee Brewers on May 8.