Tommy Hitman Hearns has knocked out Heavyweights in the gym.
Knocked out Cruiserweights in the ring.
Former 147 lb Champ.

He fought as a Cruiserweight later in his career, but he wasn't a big Cruiser.
He wasn't even a big Light-Heavyweight.

I think 154 was probably his best weight.
That was back in the same-day weigh-ins era, people didn't dehydrate 18 lbs then, by the $#!t !