Sébastien Chabal (born 8 December 1977 in Valence, raised in Beauvallon) is a French rugby union footballer who plays at number 8 in the back row of the scrum for Sale Sharks and France, and has also played as a lock for France. He earned his first cap on March 4, 2000 against Scotland. He has played 31 games for France and has scored three tries, two against Italy in the 2007 Six Nations and a game-winning score against England in the runup to the 2007 World Cup.

Chabal joined Sale from French club Bourgoin-Jallieu, making his debut against the Leicester Tigers in 2004. He is renowned for his hard-hitting and aggressive style of play, but a short temper has led to disciplinary problems, most recently on 26 February 2006, when he received a red card for stamping on Wasps player Lawrence Dallaglio. Chabal has acquired cult status at Sale, enjoying the nickname "Seabass", and also affectionately by English rugby fans as the "homme des grottes". He is well known for not shaving and his very long hair, leading to French rugby fans nicknaming him "l'Homme des Cavernes" - the Caveman.

He is also famous for a number of eccentric moments in his rugby career. A few of these include missing a tackle on an opponent and tackling the linesman instead, lurching towards the referee when blown up trying to tackle a player and whilst attempting a small kick just behind the back line, he miscued it completely and subsequently attempted to boot the ball over the posts whilst it was still on the ground. With this adding to his long hair and beard, he is a favourite amongst both the Sale and French rugby fans. He has developed a strong online following who call themselves "Chabalists.

Although Chabal is primarily a back-row player, France coach Bernard Laporte has long sought to use him as a lock. In a 2007 interview, Chabal said that Laporte called him just before the France squad was announced for the 2007 Rugby World Cup and told him, "I really want to pick you but to play second row." Chabal accepted Laporte's offer.

Masoe received a crunching tackle from France No.8 Sebastien Chabal when he played New Zealand in the Autumn Tests of 2006. This made Masoe stagger and took minutes to recover from the devastating yet legal blow from "L'homme des cavernes" or "The Caveman". Speculation into Chabal's aggressiveness could stem from when the All Blacks performed the Haka, the Kapo O Panga version, whilst the All Blacks did the controversial throat slitting gesture, Masoe was staring at his opposite number eight. This could have been the reason for the bone crunching tackle from Chabal, though there is no evidence for this.