Marie Rachel Sebag (born 15 October 1986) is a French chess grandmaster.

In 2004, she shared first place in the World Youth Chess Championship in the category girls U18 with Jolanta Zawadzka, who defeated her in the tie-break.

In 2006, she reached the quarter-finals during the Women's World Chess Championship, in which she lost to Svetlana Matveeva.

Sebag was already an IM and a WGM when she scored her second GM norm during the Hogeschool Zeeland tournament in Vlissingen in August 2007,[2] where she won a game against former FIDE World Champion Rustam Kasimdzhanov.

[3] By securing a third norm during the European Individual Chess Championship, she qualified for the title of Grandmaster in May 2008.