Is the movie-image of Frankenstein's monster (bolts in neck) public domain?

I’m working on a book. The cover may feature (cartoon) drawings of some classic movie monsters. All of them are pretty generic (mummy, Dracula/vampire, zombies, creepy creature that vaguely resembles the Creature from the Black Lagoon)—except, of course, for Frankenstein. Without that flat-top head and the electrode bolts in the neck, it just doesn’t read as Frankenstein’s monster.

Now, I thought that Universal had some sort of rights over that particular image of Frankenstein for a long time … and that it had in recent years gone into the public domain. Is that the case? Or does Universal still have the rights to the Karloff bolts-in-the-neck version of the monster? If I feature a drawing of that version of Frankenstein on the cover, am I going to run into trouble with Universal’s lawyers?

I’m not a lawyer, but I’m pretty sure you’re in the clear.

Universal may have copyright of any images from an actual movie they own. But if you’re talking about a drawing that you make or comission, they wouldn’t have a copyright over that.

Now, if they somehow have a trademark on that particular depiction of Frankenstein, then you might run into trouble.