Omar Olivares Palau (born July 6, 1967) is a Puerto Rican former right-handed starting pitcher in Major League Baseball who played for the St. Louis Cardinals (1990–1994), Colorado Rockies (1995), Philadelphia Phillies (1995), Detroit Tigers (1996–97), Seattle Mariners (1997), Anaheim Angels (1998–99), Oakland Athletics (1999–2000) and Pittsburgh Pirates (2001). He batted and threw right-handed.

In a 12-season career, Olivares posted a 77–86 record with 826 strikeouts and a 4.67 ERA in 1591+2⁄3 innings pitched.

As a hitter, Olivares was better than average as pitchers go, posting a .240 batting average (58-for-242) with 25 runs, 5 home runs and 29 RBI. Considered to be a good athlete, especially for a pitcher, he was occasionally used as a pinch runner and pinch hitter.