Anthonie Johannes Gronum (born 15 June 1985) is a South African rugby union player, currently playing with Border club side Old Selbornians. His regular position is lock.
He started his career at the Blue Bulls, making his first class debut in the 2006 Vodacom Cup. He failed to break into the Currie Cup squad and joined the Leopards in 2007, where he made 55 appearances over the next four seasons, 18 of those appearances in the Premier Division of the Currie Cup competition.
In 2011, he moved to East London to join the Border Bulldogs.