Written in response to this question:
Worg- Warg- Tell me about them?
It’d be my pleasure!
The word “warg” comes from Old Norse “vargr” (plural “vargar”), meaning wolf; without delving too deep into the etymology, it was used to refer to various giant wolves of Norse mythology, such as Fenrir (destined to swallow Odin during Ragnarok), Skoll (destined to swallow the sun), and Hati (destined to swallow the moon).
There were other wargs/giant wolves in Norse myth, often being used as mounts to various gods and giants and other extremely powerful individuals.
Does this also make Odin’s wolves, Geri and Freki, wargs? That was never really specified. But they are giant, godly wolves, meant to be the fathers of all wolves everywhere, so… Maybe? If they are, this would make not all Norse myth wargs evil.
So where did we get our modern-day, always-evil wargs with goblins and/or orcs on their backs? Just one source – Tolkien.
Tolkien was the one who decided that wargs are these giant brutish evil wolf monsters that are semi-intelligent (unlike the ugly absurd hyena mutations in the movies; in the books, they are capable of speech, even if they are honestly still incredibly daft) and willingly allied themselves with the forces of evil. But instead of being incredibly powerful, godlike beings, they were just simple monsters ridden by equally as simple monsters, like orcs.
They were often, in the books, also referred to as being paired up with Tolkien’s unfortunate idea of “werewolves” (that were really nothing like werewolves at all), though those didn’t directly appear in the LotR series itself. (Side-note: I love Tolkien’s world. I DO NOT love his wargs, and I especially loathe his supposed “werewolves.”)
And where did we get the word “worg?” That was all D&D. When oldschool Dungeons and Dragons were wholesale ripping off every single aspect of Tolkien (balor = balrog, halfling = hobbit, mithral = mithril, etc), they got into trouble for using all the exact same words as Tolkien did in what was essentially, at that time, also just Tolkien’s setting slightly rebranded. So they swapped the A for an O.
Where does that leave Game of Thrones, then, with their “wargs” that are “skinwalkers” who can “warg” (verb) into animals and stuff and see through their eyes? There were plenty of legends about people in Norse myth especially (also some in Eastern Europe, even some in Scotland) able to enter the bodies of animals while they slept.
Some werewolf legends even worked this way. But no, “warg” is not a verb, ala “warging.” That just means “wolfing,” not “entering something else’s consciousness.”
So the modern concept of wargs is just yet another major fantasy element that Tolkien alone brought into broader popular culture. Yes, he based it in Norse myth, as he did many aspects of his universe (except orcs, which were all his own creation), but he is the one who decided they’re all evil.