The Tremors franchise is a  monster series centering on the vicious attacks of subterranean worm-like creatures known as graboids. It began in 1990 with the successful release of Tremors, which spawned four direct-to-video films; three sequels, Tremors 2: Aftershocks, Tremors 3: Back to Perfection, Tremors 5: Bloodlines and a prequel, Tremors 4: The Legend Begins.