Atthasit Mahitthi (Thai: อรรถสิทธิ์ มหิทธิ) (born 13 September 1978) is a former professional Thai snooker player. Mahitthi reached the semi-final at the 2006 IBSF World Amateur Championship in Amman, Jordan, where he was eliminated by Kurt Maflin 8–4.He has earned a place on the Main Tour for the 2008–09 season by winning the 2007 IBSF World Amateur Championship, but dropped off at the end of the 2009–10 season. He had a good run in the 2008 Bahrain Championship, winning 3 qualifying matches before being paired with veteran Steve Davis. He narrowly lost 5–4 to Davis in the final qualifying round – which was perhaps unfortunate considering Davis was unlikely to play in the event due to a fixture clash, and he did withdraw a short time after.