Middle Earth/Gollum

Gollum or Smeagol stole the Ring from his cousin Deagol and murdered him. He justified taking the ring as his birthday present. It was his birthday, and so forth.

Years later, in the Hobbit, Gollum lost the Ring under the Mountain whereupon Bilbo promptly found it. After the famous Riddle Game, during which Gollum was unaware of his loss, Gollum refused to show Bilbo the promised way out and plotted to murder Bilbo, who managed to jump over Gollum to safety. Gollum cried out, "Thief! Baggins! We hates it forever!"

In the Lord of the Rings, Gollum reappears searching for the Ring and

okay, someone else finish it