Grigorij Khizhnyak (alternate spelling: Grygorii Khizhniak, Ukrainian: Григорій Хижняк; July 16, 1974 – October 5, 2018) was a Ukrainian professional basketball player.
Khizhnyak, who was a dominant defensive force in the paint, led the EuroLeague in blocks per game for two consecutive years (2001, 2002), while playing with the Lithuanian League club Žalgiris Kaunas.
Among his greatest career achievements, was his participation in the ULEB Cup (EuroCup)'s 2005 Final, while he was a member of the Greek League club Makedonikos.
Khizhnyak was a regular member of the senior men's Ukrainian national basketball team.
Khizhnyak died of a heart attack on 5 October, 2018, at the age of 44.