Gollum
Gollum is a fictional character from J. R. R. Tolkien's legendarium. He was introduced in the 1937 fantasy novel "The Hobbit", and became an important character in its sequel, "The Lord of the Rings". Gollum was a Stoor Hobbit of the River-folk, who lived near the Gladden Fields. Originally known as Sméagol, he was corrupted by the One Ring and later named Gollum after his habit of making "a horrible swallowing noise in his throat".
Legolas
Though neither Legolas's age nor his birthdate are directly given in Tolkien's writings, some passages indicate that he is far older than Aragorn and Gimli. For instance, he calls them "children" and says he has seen "many an oak grow from acorn to ruinous age". The Appendices to "The Lord of the Rings" do give Gimli's and Aragorn's birthdates: at the time of the War of the Ring, they are 139 and 87 respectively. Though his father and his kingdom appear in "The Hobbit", Legolas does not appear himself, as his character had not yet been created. Being older than Gimli, he must have been alive during the events of "The Hobbit", which take place less than a century before the Quest of Mount Doom.