Michael James Holtz (born October 10, 1972) is an American former professional baseball relief pitcher and left-handed specialist.

He played in Major League Baseball (MLB) for the California / Anaheim Angels, Oakland Athletics, San Diego Padres, and Boston Red Sox.

In 1997, he was named to the Topps All-Star Rookie Team along with fellow Angel teammate Jason Dickson.

In an eight-season career, Holtz posted a 16–19 record with a 4.76 ERA and three saves in 353 relief appearances.

Following the bulk of his MLB career, Holtz played for the Yokohama BayStars of the Japanese Central League in 2005 and had a 0–1 mark with 4.38 ERA and 22 strikeouts in 24+2⁄3 innings of work.