Swimming at the 2000 Summer Olympics – Men's 100 metre freestyle

The men's 100 metre freestyle event at the 2000 Summer Olympics took place on 19–20 September at the Sydney International Aquatic Centre in Sydney, Australia.

Netherlands' Pieter van den Hoogenband stormed home on the final lap to claim his second Olympic gold medal at these Games. He posted a time of 48.30 to hold off Russia's defending Olympic champion Alexander Popov by almost two-fifths of a second (0.40). Failing to attain a third straight triumph in the same event, Popov settled only for the silver in 48.69. Meanwhile, U.S. swimmer Gary Hall, Jr. powered home with a bronze in 48.73.

After breaking a split world record in the 4×100 m freestyle relay on the opening night, Australia's overwhelming favorite Michael Klim missed out the podium in a close race against Hall by a hundredth of a second, finishing with a time of 48.74. Klim was followed in fifth by Hall's teammate Neil Walker (49.09), and in sixth by Sweden's three-time Olympian Lars Frölander (49.22). Russia's Denis Pimankov (49.36) and another Aussie Chris Fydler (49.44) rounded out the finale.

Earlier in the semifinals, Van den Hoogenband cleared a 48-second barrier to set a new world record of 47.84, slashing 0.34 seconds off the mark set by Klim from the relay.

One of the most popular highlights in the event took place in the first heat. Dubbed as Eric the Eel, Equatorial Guinea's Eric Moussambani received a dubious honor of being the slowest Olympic swimmer in history. Two other swimmers, Niger's Karim Bare and Tajikistan's Farkhod Oripov, plunged into the pool and were cast out of the race under a no false-start rule, leaving Moussambani as the last man standing. Cheering by a large crowd, he finished a one-man heat in 1:52.72, nearly seven seconds slower than a winning time by Van den Hoogenband over double the distance a day before.