No One Dared Come Too Close!
The first Fantastic Four comic came out in November 1961. The following year, Hand of Death (1962) hit theaters. I doubt that comic-reading movie-goers failed to notice the rather striking similarity between The Thing and HoD's lead character. A quick online search doesn't reveal any formal accusations of theft/plagiarism by Marvel, but the matter is one that bears more looking into.
In any event, most online commentators agree that Hand of Death is a film with an interesting premise (experiment-gone-wrong transforms scientist into a monster with a death-touch) but poor execution. Fantastic Movie Musing & Ramblings calls it a "standard and predictable low-budget fare" and Foster On Film suggests "[t]he reason to skip Hand of Death isn't that it is particularly bad, but that it has nothing to offer."
My favorite online review of the film comes from Mr. Satanism, who notes that the mutated scientist "decides to go after his whiny, ugly, annoying girlfriend- in his car. I'm sorry, but a monster chasing you in an old station wagon isn't very scary- in fact, his reign of terror or whatever is derailed when he gets a flat tire, so he has to try to take a cab!"
Click through for the film's poster (which shows the monster with a total of 11 fingers(?), and a great small image of it terrorizing a crying little boy) and a clip of the film's opening scene.