Tõnu Õim (spelled Tonu Iym in FIDE records), born 16 June 1941 in Raasiku, is an Estonian grandmaster of correspondence chess, most famous for being the first to have won the ICCF World Championship twice, in 1983 and 1999.
In 1991 he won the Axelson Memorial.
In over-the-board play, he was awarded the Soviet Master title in 1966.
He does not hold a FIDE title for over-the-board play; however, his peak FIDE rating of 2410 indicates a player of International Master strength.