Gollum’s original name in J.R.R. Tolkien’s legendarium was Sméagol.
Sméagol belonged to a river-dwelling people related to hobbits. His life changed when he and his relative Déagol found the One Ring in the Anduin. Sméagol desired the Ring immediately, killed Déagol, and took it for himself. The Ring’s influence and his long isolation gradually transformed him into the creature known as Gollum.
The name Gollum comes from the choking, swallowing sound he repeatedly made. Tolkien uses the contrast between Sméagol and Gollum to show the character’s divided identity and the destructive effect of possession by the Ring. Sméagol is not a separate character who merely resembles Gollum; it is his earlier name.
Déagol is often confused with Sméagol because both appear in the origin story. Déagol discovers the Ring, while Sméagol claims it and begins the chain of events that leads to his exile and corruption.