Harold Thomas Mahon OBE (15 January 1942 – 19 May 2001), was a rowing coach. He coached international crews from New Zealand, Switzerland, South Africa and Great Britain to success at World Championships and Olympic Games. He also coached Cambridge University to repeated successes in The Boat Race.
Mahon was born in Wanganui in 1942. He followed his grandfather and uncle into rowing, joining Wanganui Rowing Club. He also played cricket and rugby as a hooker, and toyed with becoming a rugby coach after studying geography at Victoria University. He rowed with some success in New Zealand, but was not an international oarsman. He married Rita Wood, although they separated in 1986.
After graduating, he began teaching at Melville High School, and joined Waikato Rowing Club. Success there led to him coaching the New Zealand national team eight to two world titles in 1982 and 1983. The failure of the eight to repeat that success in the 1984 Summer Olympics led to Mahon being gradually excluded from the New Zealand coaching setup, and moving to Switzerland.