Sean Patrick Gallagher (born December 30, 1985) is an American former professional baseball pitcher.

He played in Major League Baseball (MLB) for the Chicago Cubs, Oakland Athletics, San Diego Padres, and Pittsburgh Pirates.

Gallagher also started one game for the Class-A Advanced Daytona Cubs, scattering one earned run on six hits over five innings and striking out seven.

Gallagher split time between the Double-A West Tenn Diamond Jaxx and Class-A Advanced Daytona.

In July 2009, it was announced that he will be sent to the San Diego Padres as the player to be named later in the trade for Scott Hairston.

On July 1, 2010, Gallagher was designated for assignment after Matt Stairs and Tim Stauffer were activated from the 15-Day DL.

On April 3, 2013, Gallagher signed with the Sugar Land Skeeters of the independent Atlantic League of Professional Baseball,[4] where he made 4 starts before his contract was purchased by the Rockies.

[5] He was assigned to Double-A Tulsa, where he made 12 starts, going 4–5 with a 3.00 ERA before being promoted to Triple-A Colorado Springs on July 26.