Thomas Barr (born 24 July 1992) is a retired Irish track and field athlete who competed in the sprints and hurdles.

[3] Barr won gold in the 400 metres hurdles at the 2015 World University Games (Summer Universiade) in Gwangju, South Korea with a time of 48.78 seconds.

[6][7] In August 2017, Barr was forced to withdraw from the 400m hurdles semi-final heats at the 2017 World Championships in Athletics after a bout of gastroenteritis.

[9][10][11] In June 2024, Barr won gold at the European Championships, running the third leg of the 4x400 mixed relay, passing the baton on to Sharlene Mawdsley in second place with a 44.90 split.

[1] Mawdsley ran down the leading Belgian Helena Ponette in the home strait, crossing the line in the gold medal position in an Irish record time of 3:09.92.