Frank Glennon was the captain of the Irish football team at the 1948 London Olympic Games, leading Ireland in their 3-1 defeat to the Netherlands at Fratton Park, Portsmouth on 26 July 1948. The match was played at preliminary round status, eliminating Ireland before the Opening Ceremony. The team was coached by Manchester United captain Jackie Carey.
Frank Glennon played for the Shamrock Rovers in the League of Ireland before he was selected to play on and captain the 1948 Irish Olympic football team in London, which lost in its only match to the Netherlands by a score of 3-1. Glennon was from Dublin, the son of insurance agent Francis Xavier Glennon, the namesake and founder of the family company, later known as Glennon Insurance Brokers. He later followed his father's footsteps in the insurance industry and became the chairman of the company, serving until his death.