Jamaican Usain Bolt became the first athlete to win three Olympic 100m titles by beating American Justin Gatlin to gold at Rio 2016.
Bolt, 29, ran 9.81 seconds in his final Olympics to replicate his success at Beijing 2008 and London 2012.
Twice banned for doping offences, Gatlin was 0.08 seconds behind Bolt, with Canada’s Andre de Grasse in third.
“Somebody said I can become immortal,” said Bolt. “Two more medals to go and I can sign off. Immortal.”
De Grasse took bronze in a personal best of 9.91, ahead of Bolt’s Jamaican team-mate, Yohan Blake.
There was no British interest in Sunday’s showpiece as CJ Ujah and James Dasaolu were eliminated in the semi-finals.
Bolt remains on target to leave Rio with a third successive Olympic treble, having won the 100m, 200m and 4x100m relay titles in 2008 and 2012.
“It wasn’t perfect today, but I got it done and I’m pretty proud of what I’ve achieved,” he said. “Nobody else has done it or even attempted it.
“I expected to go faster, but I’m happy that I won. I did what I had to.”
Meanwhile, Britain’s Andy Murray became the first tennis player to win two Olympic singles titles by beating Argentina’s Juan Martin del Potro in Rio.
An emotional Murray, 29, secured a thrilling 7-5, 4-6, 6-2, 7-5 victory to make it GB’s most successful day at an overseas Games with five gold medals.
The see-saw match featured 14 breaks of serve in front of a raucous crowd.
Murray’s win comes five weeks after he claimed his second Wimbledon title and four years after London 2012 success.
Murray said the final was one of the toughest he had played in and cast doubt on the chances of winning a third gold in Tokyo in 2020.
“Four years is a long time and so many things can change,” he said. “Who knows about Tokyo? At 33, I’m not sure I’ll be at the same level.”