Berserker - Fred Saberhagen

Long ago, in a distant part of the galaxy, two alien races met-and fought a war of mutual extinction. The sole legacy of that war was the weapon that ended it: the death machines, the BERSERKERS. Guided by self-aware computers more intelligent than any human, these world-sized battle craft carved a swath of death through the galaxy-until they arrived at the outskirts of the fledgling Empire of Man.
These are the stories of the frail creatures who must meet this monstrous and implacable enemy-and who, by fighting it to a standstill, become the saviors of all living things.
This is Saberhagen's classic book length collection of the first eleven Berserker stories. Meet Berserker hunter extraordinaire Johann Karlsen, his evil brother Felipe Nogara, The Third Historian of the Carmpan Race, gallant fighters of the killer machines and the deranged killer machine, Mr. Jester.