I have to agree with the many who said Frankenstein (Frankenstein’s Monster, to you purists. But the creature was listed as “Frankenstein” in theater bills long before the movie came out). Before Jack Pierce put all that Fuller’s Earth, collodion, and other makeup on Boris Karloff, there was no single agreed-upon image of what the Creature looked like. Usually he was drawn as an oversized guy with hair that was too long or too plentiful. At least in some cases he was oddly and vividly colored (it’s hard to tell from black and white illustrations what color he was supposed to be).
but that Pierce makeup really was iconic, giving concrete and instantly-recognizable form to the Creature, so that today you’ve got plenty of non-royalty-paying depictions that are undoubtedly supposed to represent him. That flat-topped head, the bolts in the neck, the head scars. The coloring that was actually blue on-set, was supposed to be ghastly paleness, but which eventually standardized as green. This was nothing like Shelley’s description of the Monster, and faithful renditions deliberately shy away from it, but it still appears in movies, live shows, cartoons, and more. You can’t get much more iconic than that.
By contrast, there have been lots of “Creature from the Black Lagoon”-types, with many and wild variations. King Kong is often represented as 'just a gorilla", and no effort is generally made to make that gorilla look like Willis O’Brien’s masterpiece (The remakes and the Japanese versions never even tried).
Runners up:
Dracula – The appearance and costume of the “classic” Count Dracula, as Skal has pointed out, derive from the Hamilton Deane/John Balderson stage play. If Dracula is going to be part of a parlor drama, he has to look as if he’d fit in a parlor. And the voluminous cape with the high collar were needed for the stage “disappearance” of the real actor when he turns into a bat. Much of this was retained for the Universal film version, even though it wasn’t strictly necessary, but it was after all, a filmed version of the play. And it added the needed atmosphere. The costume was retained through the Universal films and even into the Hamer and other 1960s versions, so it was inevitable that Sesame Street’s The Count ended up as a tux-earing cape-wearing easter european-accented being. Again, if you want to be instantly recognized as a vampire, you wear a cape and effect the accent, not wear sullen goth looks and sparkle makeup. (Nosferatu-like appearance has been gaining in recent decades, especially since Herzog’s remake and the first TV version of Salem’s Lot revived the image, and Shadow of the Vampire played on it. But the Rat-faced vampire is still no competition for the classic evening-suited and caped Dracula.)
Werewolf/Wolfman – Universal did give us the classic Werewolf/wolfman, though. Before Henry Hull in The Werewolf of London, the werewolf had been a human who turned into a wolf. Hollywood gave us the man/wolf hybrid creature that haunted the movies, with its upright human stance, but hairy face (and often pointed ears)I’m convinced they did this because a.) You can’t count on wolves to act and do what you want, and look menacing and evil; b.) The makeup gave the actor a chance to emote, for which you need a most-recognizable human face; c.) any sort of puppet or animated model would be seriously unconvincing, and expensive. So Hollywood created this monster almost out of whole cloth. again, it was widely copied without paying royalties, so you have similar human wolves in other company’s movies, and in comics, images, and now videogames and the like.
