Tim Montgomery (born January 25, 1975) is an American athlete, and holder of the World Record in the 100 m as of September 14, 2002.

Born in Gaffney, South Carolina, Montgomery was initially a basketball and American football player, before trying out for athletics. Montgomery did not qualify for the 1996 Summer Olympics 100 m, although he did compete in Atlanta in the heats of the 4 x 100 m relay team that eventually finished second. He qualified for his first major international tournament in 1997, and won the bronze medal at those World Championships, finishing third behind Maurice Greene. Two years later, he came sixth in the individual final, but won the gold medal with the US relay team.

Montgomery did not qualify for the individual event of the 2000 Summer Olympics, though he again ran as an alternate in the heats of the relay event; in the final, the USA won the gold medal.

The greatest moment in Montgomery's career came in September 2002, as he broke Greene's 100 m World Record by 0.01 seconds. With a tailwind of 2.0 m/s (the maximum allowed), Montgomery ran 9.78 to earn the title "fastest man on earth".

Montgomery did not qualify for the 2004 Summer Olympics, finishing seventh in the final of the United States Olympic trials. Before the trials, however, he was charged with using illegal performance-enhancing drugs, by the US Anti-Doping Agency. While he has not returned a positive drug test, according to press reports he has testified to the agency that he, along with a number of other prominent athletes (including baseball mega-star Barry Bonds), obtained steroids and human growth hormone from BALCO, a laboratory near San Francisco. The USADA has sought a lifetime ban on Montgomery, who is appealing to the Court of Arbitration for Sport. Marion Jones, his partner and the winner of the women's 100 metres at the 2000 games, is also under investigation.

Montgomery and Jones have one child.