The runner is 22 year-old Shaunae Miller of the Bahamas.
She competed in the 400m women's final against American, Allyson Felix.
Felix ran the fastest qualifying time for the final and won both of the preliminary races. She also came into Rio with the fastest personal best time in the 400m event at 49.26 seconds. She was expected to win the gold.
Miller dove for the finish just towards the end of the race.
She finished with a time of 49.44 seconds. Felix finished in 49.51 seconds.
Miller ran for the University of Georgia and was an NCAA champion.
Her win in the 400 meters comes just 48 years after her great-uncle, Leslie Miller, competed in the 1986 Olympic Games for the Bahamas as well.
Miller's was named the first place winner of the 400m final.
Look at how close that was.
Following her win, Miller said, “I don’t know what happened."
She told Australia's Channel 7, "My legs started to get a little heavy and I was telling myself that I wanted it so bad and I just did whatever it took. Now I’m coming home with a gold medal, so it is such an amazing feeling for me.”