After becoming a major in the Confederate Army, Jasper was set upon by the vampire Maria, who proceeded to turn him. After the transformation, Jasper aided Maria in her creation of a newborn vampire army which successfully conquered the feeding grounds of Texas. However, over the next decades, Jasper became tired of this violent and bloodstained life, because he could feel the emotions of those he killed, which eventually became too much for him. In 1940s, he left his bloodthirsty coven to become a nomad. In 1948, he met Alice, the love of his life, and with her joined the peaceful Cullen family - a coven of vegetarian vampires. By living a vegetarian, he was freed from the emotions that so depressed him.
He is portrayed by Jackson Rathbone in the movie adaptations.