Michael Richard Weir, CM, O.Ont (born May 12, 1970) is a Canadian professional golfer on the PGA Tour. He spent over 100 weeks in the top-10 of the Official World Golf Rankings between 2001 and 2005.

Weir was born in Sarnia, Ontario. He grew up in the Sarnia suburb of Bright's Grove, Ontario, where he learned to golf at Huron Oaks Golf Course, and was coached there by Steve Bennett. He attended St. Michael Elementary School in Bright's Grove and St. Clair Secondary School in Sarnia, winning the Ontario Junior Championship in 1988. He is a graduate of Brigham Young University (majoring in Recreation Management), and won the Ontario Amateur Championship in 1990 and 1992. He tied for 2nd at the 1991 Canadian Amateur Championship, and finished clear second in that event in 1992. He was an All-American selection at BYU in 1992 on the Second Team.

He turned professional in 1992, and started on the Canadian Professional Golf Tour, where he won three events. He also played some events on the Asian PGA Tour early in his career. He first reached the PGA Tour in 1996, but lost his playing privileges, due to insufficient performance. He had to requalify, and did so by winning the final Qualifying School tournament.