Sam Uley is the leader of the La Push pack. His father, Joshua Uley, abandoned him and his mother when he was very young and thus Sam was forced to assume much adult responsibility at an early age. Before becoming a wolf, he was romantically involved with Leah Clearwater, his high school sweetheart. His relationship with her started to fall apart after his transformation because he was forbidden to tell her what he had become. Their relationship ended when Sam imprinted on Leah's second cousin, Emily, and broke every promise he made to Leah. According to Jacob, Sam feels guilty for betraying Leah and responsible for the bitter person she has become. When he phases, he is pure black and the largest wolf, until Breaking Dawn when it is noted that Jacob has grown taller. He is the pack Alpha, but not by blood; that role is Jacob's, who allowed Sam to lead the pack until Breaking Dawn.
Solomon Trimble was credited as "Jacob's friend" in the Twilight film, but was widely recognized as playing the role of Sam. In The Twilight Saga: New Moon, Sam is portrayed by Chaske Spencer.