Before becoming Gollum, J.R.R. Tolkien’s character was named Sméagol.
Sméagol belonged to a river-dwelling people related to the Stoors, a kind of hobbit. On his birthday, he and his relative Déagol discovered the One Ring in the Anduin. Sméagol wanted the Ring immediately, murdered Déagol for it, and was eventually driven away because of his increasingly corrupt and antisocial behavior.
He hid beneath the Misty Mountains for centuries, where the Ring prolonged his life and warped his body and mind. His repeated choking sound inspired the name “Gollum.” Tolkien presents Sméagol and Gollum as linked aspects of one damaged person, with occasional traces of the earlier self remaining.
Déagol was the finder of the Ring on that occasion, not Gollum’s earlier name. Gríma is a different character, associated with Rohan, and Frodo is the later Ring-bearer.