Gollum originally had the name Sméagol in J.R.R. Tolkien’s The Lord of the Rings.
Sméagol belonged to a river-dwelling people related to the Hobbits. On his birthday, he and his relative Déagol found the One Ring while fishing in the Anduin. Sméagol wanted the Ring immediately, killed Déagol when Déagol refused to give it up, and eventually became the creature known as Gollum.
The name Gollum comes from the choking or swallowing sounds he makes. Tolkien presents the character as physically and morally transformed by centuries of possession and isolation, while still retaining traces of Sméagol’s earlier personality. Frodo’s treatment of him recognizes that inner conflict, unlike the harsher approach taken by others.
Déagol is frequently mistaken for Gollum’s original name, but Déagol is the relative who discovers the Ring with him. Sméagol is the correct earlier identity.