Sport: Rugby
Position: Centre
D.O.B: 1979-07-10
Club(s): Natal Sharks
Province: KwaZulu Natal
Nationality: South Africa

Marius is a South African rugby union player who plays as a centre for ASM Clermont Auvergne in the French Top 14. He has previously played for the Free State Cheetahs and Western Province in the Currie Cup and the Stormers and the Central Cheetahs in the Super 14. He was a member of the 2004 Springbok squad that won the Tri-Nations. In the Boks' home match at Ellis Park in Johannesburg against the All Blacks, he became only the second Springbok in history (after Ray Mordt in 1981) to score a hat-trick of tries against the All Blacks. Joubert was also for a time South Africa's leading try scorer in Tri Nations , with six tries, before being overtaken by Breyton Paulse