Thomas Stephen Gorzelanny (born July 12, 1982 in Evergreen Park, Illinois) is a Major League Baseball pitcher for the Chicago Cubs. After graduating from Marist High School in Chicago, Gorzelanny played junior college ball at Triton College and spent the 2002 summer playing for the St. Cloud River Bats of the Northwoods League. He was drafted by the Pirates in the second round of the 2003 Major League Baseball Draft after playing out his college career at the University of Kansas.

Gorzelanny spent most of the 2005 season with the Double-A Altoona Curve, but made his Major League debut with the Pirates on September 20, 2005. At the beginning of the 2006 season, he was optioned to AAA-Indianapolis Indians. On June 29, 2006, the Pirates called Gorzelanny up to replace Oliver Pérez in the pitching rotation. He made his season debut on July 1 against the Detroit Tigers.

On July 1, 2007, Gorzelanny was selected as one of the five players in the National League that would be chosen from a final fan vote for the last spot on the NL roster for the 2007 MLB All-Star Game.