An American novelist, short story writer and essayist whose published work is almost entirely in the science fiction genre. He explored sociological, political and metaphysical themes in novels dominated by monopolistic corporations, authoritarian governments and altered states. In his later works, his thematic focus strongly reflected his personal interest in metaphysics and theology.

In addition to 44 published novels, he wrote approximately 121 short stories, most of which appeared in science fiction magazines during his lifetime.