scary fighters

[Trainer Monkey]

All of the above
But for very different reasons, and Ill ad for another different reason

Hearns,he hated you, or it least looked that way when you saw his eyes
Tyson, just because he was a force of nature,anybody who doesnt fear earthquakes is a moron
Liston, because you could see in his eyes,that he honestly viewed you as nothing more then an obstacle between him and the winners purse

The ones Im adding

Foreman,just for the knowledge that he could end you with one punch
Ali,it wasnt enough for him to just beat you, he wanted to punish you for the audacity of climbing in to his ring. If you won you were going to look bad doing it,If you lost.................

[killersheep]

Tyson IMO

[Dark Lord Al]

none more fearsome than Marvin Hagler , looked mean , looked tough , was mean , was tough

[Kel]

Valuev sure looks scary till he starts fighting. Tyson, prime or not was always dangerous and for that reason he was scary.

[killersheep]

Valuev sure looks scary till he starts fighting. Tyson, prime or not was always dangerous and for that reason he was scary.

Not to mention he intended to eat your children as well.

[leggy]

Valuev sure looks scary till he starts fighting. Tyson, prime or not was always dangerous and for that reason he was scary.

Not to mention he intended to eat your children as well.

and he could fight with a broken back

[donnydarkoIRL]

Ruben Carter looked scary as hell.
I imagine many who faced Julian Jackson were terrified.

Tyson obviously, Liston, George Foreman, Aaron Pryor, Antonio Margarito, Gerald McClellan, Ray Robinson.