I missed maiden round in setup so not sure if scope is limited to film or otherwise.
If we're talking folkloric as well as literary and all that, Dracula and Frankenstein are musts. These two embody our greatest fears + fascinations as people and (should) resonate with all. A lycanthropy entry is a third I'd like to see but I guess didn't survive earlier rounds?
That said and in addition to Dracula, I voted Jigsaw because he's also a pretty powerful amalgam of where we're at as people nowadays. The character feels wronged (his wife's cancer went misdiagnosed, iirc) and goes full lex talionis in righting things by balancing scales per his own perspective or worldview. Films are rad too, IMO.
If film only, Freddy then is a must, I reckon. Good entry. Like Dracula who flips the script on night versus day, death versus deathlessness, mortality, and the complex morality of it all, Freddy is an extension of our nightmares and that REM sleep when we experience nightmares is alienable to the human experience.
Michael Myers above Frankenstein is crazy, IMO. I grew up with the films though; I get it. Frankenstein has never really been done right in film in the modern era. I think there's an upcoming Franken film, actually? Maybe he gets his dues this time around.
Fun poll.