Sébastien Lareau (French pronunciation: [sebastjɛ̃ laʁo]; born April 27, 1973) is a former professional tennis player.

He became the first Canadian to win a Grand Slam title by winning the 1999 US Open men's doubles with his American partner Alex O'Brien.

The right-handed Lareau achieved a career best singles ranking of world No.

He has a career ATP Tour event win–loss record of 99–137.

His victories included the 1996 and 1998 Stuttgart Masters, the 1999 London Queen's Club International Series, the 1999 US Open, the 1999 Paris Indoor Tennis Masters, and the 1999 ATP Doubles Championships events, all partnering Alex O'Brien; the 1999 Washington International Series and 2000 Memphis International Series Gold events, partnering Justin Gimelstob; and the 2000 Montreal/Toronto Tennis Masters and Sydney Olympics, partnering compatriot Daniel Nestor.