A lot of the examples I was thinking of have already been said. One I'm surprised no one has mentioned is Jerry Quarry going to a knee after a Frazier body shot.
Virgil Hill had a good chin but was kod by Jones with a body shot. His only other loss inside the distance was when he didnt come out for the 9th against Mormeck.
To be fair, I saw one of the stoppages Pacman suffered and it was not on the up and up to me. It looked clear that he was his directly hit on the cup, went backwards and cracked his head on the canvas and they stopped the fight. That should have been ruled a no contest or even DQ. Poor kid was a teenager and I remember the commentator saying Pac's arrogance was to blame and that a head shot did it. I sure as hell didn't see anything they were talking about.
This was Pac's second KO loss, for anyone who hasn't seen it: [yt]AU7TsuRbwYo[/yt] For obvious reasons, he never fought at this weight class again.