Killer vs. Killer.
Lecter probably has the intelligence advantage, but Riddick probably has the physical advantage. Tough to say who is more ruthless overall, though most might just pick Lecter for the whole flesh eating thing.
The setup: (each on the other’s home turf so to speak)
#1: The building/scene is that one in SOTL where Lecter steals that guys face and does the ol’ switcheroo (spoiler?)
#2: Your standard a prison/slam of the Riddick universe.
Hannibal Lecter killed the lunatic in the cell next to him by talking him into swallowing his own tongue. He managed to organize an attack on Wil Graham that left Graham disfigured and his marriage wrecked, without ever leaving a maximum security prison.
Lecter in a walk.
Lecter is the Batman of the fictional serial killer world. Give him enough time to work his magic and no one will survive.
For Lecter, you’d need Sherlock Holmes.
Actually, I’d say Holmes would be at a considerable disadvantage, too. Lecter’s greatest strength lies in his ability to predict with precision how a person will react to this or that stimulus. Holmes would have no particular advantage.
A robot might. Any of the villainous Terminators would probably win out over Dr. Lecter, because they have no psyche to probe and are physically stronger.
Or perhaps a true madman - not a person with a psychiatric condition that Lecter could diagnose and take advantage of, but rather one whose actions are literally random.
I think he would deal with them like the killer pigs.
Head to head, physically, Riddick wins. You can’t rely on psychological manipulation in the short term, & Riddick isn’t dumb enough to let some talker get hooks in him.
They say your most of your brain shuts down in cryo-sleep.