It's hard to get a one-punch knockout in boxing, but it's even harder to get it in the opening seconds of a bout. The nine boxers on this list do just that, and they make it look easy.
With power and accuracy, they manage to put their opponents on the canvas and sometimes to sleep with one vicious blow.
Featured boxers include Nigel Benn, Mike Tyson, Bernard Hopkins and Gerald McClellan.
"The Dark Destroyer" Nigel Benn was 5-0 as a professional and looking for his sixth consecutive knockout.
If you want to see some devastating knockouts that are as close to resembling that of a young Mike Tyson, Benn is the one to watch. He walked through opponents like they were nothing.
Once again, Nigel Benn comes out and makes a quick statement with one of the most vicious and fastest knockouts of his career. He was 10-0 at the time with 10 knockouts, seven of which came in the first round
His opponent was Ian Chantler.
Benn would go on to have a record of 42-5-1 with 35 knockouts. He also became the WBC light-middleweight champion and defended the title numerous times.
The fastest knockout in amateur boxing history was by nobody other than "Iron" Mike Tyson.
The quick and ferocious KO over Dan Cozad was a sign of what was to come for the future heavyweight champion of the world.
Tyson would go on to turn pro three years later where he earned 19 consecutive knockouts in his first 19 professional bouts.
Samoan boxer Jimmy Thunder was coming off a decision loss to the "Quiet Man" John Ruiz two months earlier.
He planned on using Crawford Grimsley, who was 20-1 at the time, to make a statement.
It only took 13 seconds and one punch to put Grimsley to sleep.
With an 85 percent knockout percentage over 31 victories, Gerald McClellan was widely considered to be one of the hardest punchers in boxing.
His power took him all the way to beating John Mugabi for the WBO middleweight title.
His second defense of the title came against Jay Bell. It only lasted 20 seconds.
Former middleweight and super-middleweight boxer Chris Eubank was one of England's finest.
This bout versus Reginaldo Dos Santos was for the vacant WBC International Title. Santos was 11-3 and hoping to take out the undefeatd Eubank in front of a crowd at the Royal Albert Hall in Kensington, London, England.
20 seconds and one-punch after the bell, Santos was on the canvas.
Naseem Hamed didn't waste any time in putting Said Lawal on the floor in his first defense of the WBC featherweight title.
The referee, who should've stopped the bout, let Lawal continue for a few seconds before he was dropped again, waving off the fight for good.
To put things into perspective, Hamed's charismatic entrance was 10 minutes long, and the fight was only 35 seconds. At least the fans got their money's worth in some way or the other.
It was 1996 and Bernard Hopkins had just won the vacant IBF super-middleweight championship against Segundo Mercado.
His first defense would be against Steven Frank, who was 15-2-1 at the time.
After a very brief feeling out process, Hopkins unloaded a right hand that put Frank on his back 15 seconds into the bout.
Jeremy Williams had nine knockouts in a row, but his opponent Arthur Weathers was hoping to make that come to a end.
Unfortunately for Weathers, he got dropped just seconds into the bout. The referee called it off just seconds later, giving Williams the 10-second KO.
Three punches, three knockdowns.
Sechew Powell was 15-0 going into his ShoBox bout with undefeated prospect Cornelius Bundrage.
Bundrage was 21-0, and both boxers put each other on the canvas right after the opening bell. They both jumped to their feet, but Powell put Bundrage down with one punch immediately after.