Ingemar Johansson was a Swedish boxer with a thunderous punch and plenty skill in the late 1950s to early 1960s.
He decimated Henry Cooper (who gave Muhammad Ali trouble) and knocked down an undefeated Eddie Machen three times en route to a brutal first-round knockout.
Sonny Liston struggled to win a 12-round decision against Machen.
Johansson's shot at the world heavyweight title came against Floyd Patterson in 1959. Johansson floored Patterson six times in Round 3 before the fight was stopped.
In two rematches, Patterson would get his revenge twice over, but the Patterson-Johansson trilogy remains one of the most brutal and entertaining trilogies of all time.
Johansson fought a bit more until he was knocked down in the final seconds of a fight with journeyman Brian London in 1963.
Johansson would get up to beat the count and win the decision, but the bad press he got from the moment caused him to immediately retire. He was only 30 years old.
There were discussions to try to match him up with Sonny Liston for another shot at the world title. Liston had just stopped Patterson twice to win the world title.
Had Johansson continued, a slugfest between Liston and Johansson would've likely been fight of the decade. Johansson's slightly higher mobility, youth and higher boxing IQ could've picked up the win.
Next stop, likely a young Ali. From there, we'll never know.