Thomas E. Allen (born March 14, 1970) is an American college football coach who is the defensive coordinator at Clemson University.

[1] Following their college graduation from Maranatha Baptist University, Allen and his wife moved to Florida, where both began teaching.

[1] Allen's first coaching job was with Temple Heights Christian School in Tampa, Florida, as defensive coordinator.

Allen started in 1992; he took over as head coach during the 1993 season after the resignation of Steve Lewis, who remained the athletic director.

[2] In 1994, his only full season as Temple Heights head coach, Allen went 8–3 and lead his team to their first playoff appearance since 1976.

[3] The following year, Allen left to become defensive coordinator at Armwood High School in nearby Seffner, Florida.

After just one year at Marion, Allen took the defensive coordinator job at Ben Davis High School in Indianapolis.

The head coach at Ben Davis was Dick Dullaghan, whom Allen had come to know through the former's football camps in Lakeland, Florida.

Allen succeeded Neal Neathery, who had left to become defensive coordinator at the University of Texas at San Antonio.

In 2011, Allen served as the assistant head coach at Arkansas State, his first position with a Division I FBS program.

[citation needed] On December 17, 2014, Allen was named defensive coordinator at South Florida under third-year head coach Willie Taggart.

[14][15] Allen was hired on January 15, 2016, to serve as defensive coordinator on head coach Kevin Wilson's staff at Indiana.

After just one season, Allen engineered one of the top defensive turnarounds in the country with the team improving in every major statistical category against a schedule featuring four top-10 opponents, a program first.

[citation needed] On December 1, 2016, Indiana athletic director Fred Glass named Allen head coach after Wilson's sudden resignation, forcing Allen to make his coaching debut during the team's final game of the season at the 2016 Foster Farms Bowl.

This made Allen the lowest-paid head coach in the Big Ten, although various bonuses could take his total compensation above $3 million.

During his first two seasons as head coach, a school-record number of players earned conference honors and a school record were drafted or invited to NFL camps.

More than 30 seniors and juniors had departed and the team added 13 players from the transfer portal, along with five new assistant coaches, two new coordinators, and Allen himself returning as the defensive play-caller for the first time since 2018.