Francois John Mostert (born 27 November 1990) is a South African rugby union player for the South Africa national team and Gloucester in the Premiership.
His usual position is lock.
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.He also played for UP Tuks in the 2010, 2011 and 2012 Varsity Cup competitions.
He joined Gloucester prior to the 2018–19 English Premiership.Mostert was named in South Africa's squad for the 2019 Rugby World Cup.
South Africa went on to win the tournament, defeating England in the final.