Sue Clearwater is a Quileute Native American woman, the mother of Leah and Seth Clearwater who phased into werewolves (shapeshifters) sometime in 2006.
Not much is known about Sue, since she played a minor role in the Twilight saga. She was widowed in 2006 when her husband, Harry, who was on the Tribal counsel, died of a heart attack, believed to have been caused by the knowledge of Leah turning into a werewolf.
She played a brief part in New Moon when she was seen playfully chiding her husband to eat healthier at a house party, her next appearance was at a bonfire where she was took her husband's place on the Counsel. She is next mentioned in Breaking Dawn, when she makes an appearance at Bella and Edward's wedding-it is noted that her hair is cropped short-like her daughter, Leah's as a show of solidarity. It is implied later on in Breaking Dawn, that she and Charlie Swan, Bella's father, might be having a romantic relationship.
