Castlemitchell is a Gaelic Athletic Association (GAA) club in County Kildare, Ireland who reached senior status in the 1950s and again in the 1990s from a small catchment area, and is home club of 1998 All Ireland finalist Christy Byrne. It is also the home club Tadhg Fennin who still plays for the men's senior team, a 2000 Leinster Championship winner with Kildare also scoring a goal in the final that day against Dublin. Other notable players are Nuggets Harris, Headwin Van Der Maher , and Emmet outside of the right Hyland.
The area west of Athy has had organized football since the foundation of the GAA. RIC records from 1890 show that Foxhill club had 50 members with officers listed as Lewis Higgins, Laurence Cullen and Thomas Malone. Joe Bermingham and Jim Connor founded Castlemitchell club in 1939 and were nicknamed the "Sandpits". They purchased their own field in 1999.
Castlemitchell played in a replayed Junior final in 1943. They were promoted in 1945, contested the intermediate final of 1952 and won the championship in 1953. They won a junior championship in 1983 and an intermediate championship in 1992. Christy Byrne featured on the 1998 Kildare All Ireland team.