Frankenstein's creation (let's call him "Adam")
I agree that Adam is probably the best name for the book character, but I've got nothing against calling Frankenstein's Monster just "Frankenstein." One way of looking at it is that he's Frankenstein's son, and is thus entitled to the family name. Another way is that he's Frankenstein's creation, and thus could be called a Frankenstein by the same logic as a sandwich, a leotard, a theremin, Braille, or anything else named after its inventor.
I find it interesting that in
Son of Frankenstein, Basil Rathbone's title character complains about the public tendency to refer to the monster as "Frankenstein." So that convention was around pretty early on, enough that the filmmakers got metatextual about it.
The Toho duology not only referred to the creature himself as Frankenstein (or
Furankenshutain), but in the sequel referred to the mutated original and his cloned offspring as "Frankensteins" collectively, like a species name. The sequel gave the original creature, or rather the Sasquatch-like giant he'd mutated into, the name Sanda, while his evil clone was Gaira. (The American version,
The War of the Gargantuas, edited out any Frankenstein connections, perhaps because American audiences would be confused to hear the name associated with Bigfoot monsters.)
As for the movies making "Adam" a speechless "brute", well, they contributed and popularized misconception, but Universal was not the "source" of that interpretation.
Note also that
The Bride of Frankenstein showed that the Monster could learn speech and was anything but a brute. He lost that ability in the subsequent film due to brain damage (and due to Karloff preferring the character to be mute), but he regained it once Ygor's brain was placed in his body in
Ghost of Frankenstein (along with his vocal cords, apparently, since they dubbed Lugosi's voice onto Lon Chaney). Which is why Lugosi played the Monster in
Frankenstein Meets the Wolf Man -- except they then decided to cut out all his dialogue and make the Monster mute again for no apparent reason. So they kind of went back and forth on that one.
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