Billy Cosh

William Cosh (born March 5, 1992) is an American college football coach. He is currently the head football coach for Stony Brook University.

Playing career
Cosh attended Arundel High School from 2006 to 2009. He became the starting quarterback in his junior year, where he broke seven state records throughout the season including most passing yards (3,909) and most touchdown passes (56) in a season. In his senior year, he threw for 3,913 yards and 56 touchdowns, setting state records for career attempts (909), completions (594), passing yards (7,433) and touchdowns (112).

Cosh first committed to Kansas State, where his father Chris was the defensive coordinator. He redshirted his freshman season. He transferred to James Madison after the season, following a visit from their head coach Mickey Matthews which convinced him there was an opportunity for him there. However, he was at the bottom of the quarterback depth chart and did not play. Cosh would regret his first transfer as "a rash decision." In 2012, he transferred to Butler Community College but tore his ACL in the NJCAA junior college championship game, ending a season where he threw for 2,856 yards and 25 touchdowns.

He committed to Houston in December 2012. He was cleared to return in July 2013. In 2014, Cosh made his NCAA debut, completing five of nine passes for 32 yards in three games.

Coaching career
Cosh became his coaching career at Concord. He served as a graduate assistant and quarterbacks coach for Indiana from 2016 to 2017. Then, he was hired at VMI, where he was the wide receivers coach before being promoted to offensive coordinator and quarterbacks coach, leading their "Air Raid" offense. After four seasons, he was named Richmond's offensive coordinator. In his one season at Richmond, the Spiders had a top 20 offensive SP+ rating and advanced to the second round of the FCS playoffs. Cosh was hired by Western Michigan as their offensive coordinator before the 2023 season.

On December 13, 2023, Cosh was named the third head coach in Stony Brook Seawolves history. At 31 years old, Cosh became the second-youngest current Division I head football coach.

Personal life
Cosh is the son of football coach Chris Cosh, who served as defensive coordinator on multiple FBS college football teams.