Onan Orlando Thom (born April 11, 1984) is a Guyanese former swimmer, who specialized in sprint freestyle events. Thom qualified for the men's 100 m freestyle at the 2004 Summer Olympics in Athens, by receiving a Universality place from FINA, in an entry time of 54.14. He challenged seven other swimmers in heat two, including three-time Olympian Aleksandr Agafonov of Uzbekistan. He earned a sixth spot in 55.24, more than a second off his entry time. Thom failed to advance into the semifinals, as he placed fifty-ninth overall out of 71 swimmers in the preliminaries.