Does it irk you that most people seem to refer to Heracles as Hercules, even when they’re talking about the Greek version of the hero?
Eh… not really. It’s not often that the distinction is important, unless you’re in a technical context, since they’re basically the same guy (unlike, say, Ares and Mars, where the Italian conception of the god is actually different enough that it sort of matters which one you’re talking about). The ancient Greeks had at least three different ways of spelling “Heracles” anyway.
Cavedraconem adds: I don’t know, I think that Hercules Olivarius, as protector of olive merchants, is a pretty important Roman version of Hercules whom one might want to specifically refer to.
Well, I did specify “unless you’re in a technical context.” But yes, if you’re a classicist talking about Roman religion and you call him “Heracles” then you should absolutely be shot.