Emmett Cullen (born Emmett McCarty[4]) is Rosalie's husband, Carlisle and Esme's adopted son, and Edward, Alice, and Jasper's adoptive brother. Emmett is described as being tall, burly, extremely muscular, and, to most humans, the most intimidating of his adoptive siblings. He has slightly curly dark hair and dimpled cheeks.

Emmett was 20 and living in Gatlinburg, Tennessee, in 1935 when he was mauled by a bear. The injuries from the attack were severe and he was found by Rosalie, who had been hunting in the area at the time. Rosalie, who was reminded of her friend's baby having the same curls, dimples, and innocent appearance, carried him over a hundred miles to Appalachia where Carlisle Cullen was, asking him to spare Emmett's life by turning him into a vampire. Emmett joined Carlisle's coven, but initially had trouble adjusting to the family's diet of animal blood. In Twilight, Emmett is at first wary of Bella, but eventually warms up to her. He often teases her for her clumsiness and constant blushing, and votes in favor of her becoming a vampire in New Moon. In Breaking Dawn Emmett jokingly makes innuendos about Bella's sex life, until being silenced when she defeats him in an arm wrestling match.