The Berserker series is a series of space opera science fiction short stories and novels by Fred Saberhagen, in which robotic self-replicating machines strive to destroy all life. These Berserkers, named after the human berserker warriors of Norse legend, are doomsday weapons left over from an interstellar war between two races of extraterrestrials. They all have machine intelligence, and their sizes range from that of an asteroid, in the case of an automated repair and construction base, down to human size (and shape) or smaller. The Berserkers' bases are capable of manufacturing more and deadlier Berserkers as the need arises.