Emile Griffith and Benny "Kid" Paret was the most memorable to me as Paret was killed in the ring because the ref didn't stop it soon enough.
Paret was against the ropes, as he would start to go down and Griffith would hit him with an uppercut and stand him up again. I don't know how the ref couldn't tell he was out on his feet. Griffith did what trained boxers do-keep swinging until the bell or ref say stop.
My Dad (rip) was yelling at the tube for the ref to stop the fight.