@KingMab indeed, jack the ripper is very weak as "the most hated", doesn't even register a blip in that scale, sure he was notorious and for the time and place instilled fear, but that fear was in the slums not the "well do" part of the city.
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@yarielist said, you have to draw a distinction, hitler sure is most hated but he wasn't a "hands on" guy, not really fir for fighting a deathmatch, for that you have to turn up to the real monster, i mean, there are plenty more savage and effective killers.
Also jack the ripper targetted female hookers, hardly a target that has the physical prowess to fight back.
Some said vlad the impaler, but again ti's not like he personally hunted impaled people, again, not hands-on.
Better choices would be brutal serial killers of adult humans(i mean, a children serial killer might be bad, but not really fit for a fight, like Ed Gacy), probably some soldier of fortune, the zodiac killer, charles manson, etc.