Franco John Mostert (born 27 November 1990) is a South African professional rugby union player for Honda Heat and the South Africa national team. His usual position is lock. He was one of the members of the winning Springboks in the 2019 Rugby World Cup in Japan. He joined the Golden Lions for the 2013 season, but was seriously injured in a car crash shortly after joining, which ruled him out until at least the end of 2013. He fully recovered and was included in the Lions squad for the 2014 Super Rugby season and made his debut in a 21–20 victory over the Cheetahs in Bloemfontein.