Fred Saberhagen's Berserker series is a space opera in which robotic self-replicating machines intend to destroy all organic life. These berserkers, a doomsday weapon left over from an interstellar war 50,000 years ago, are killer spaceships furnished with machine intelligence, operating from asteroid-sized berserker bases where they are capable of building more Berserkers and auxiliary machines. The name is a reference to human berserkers, reflecting the Berserker's violence and singleness of purpose.