“Itself!”, A. E. van Vogt, 1963 – An AI submarine left-over from a past war patrols the waters, paranoid and territorial. By luck, it destroys the crew of an alien invasion craft. Those in charge realize the value of the being and create another “king” of the waters.
Comments: Read in Ackermanthology.
Author: Wikipedia: “Alfred Elton van Vogt (April 26, 1912 – January 26, 2000) was a Canadian-born science fiction author regarded as one of the most popular and complex science fiction writers of the mid-twentieth century: the ‘Golden Age‘ of the genre.”