Orion by Ben Bova (Orion #1) | Vintage Science Fiction

Used; Paperback - good; 1st edition, 1st printing, cover has some wear, front cover has some damage, spine has wrinkles, discoloration, spine cocked. 

John O'Ryan is not a god...not exactly. He is an eternal warrior destined to combat the Dark Lord through all time for dominion of the Earth. Follow him, servant of a great race, as he battles his enemy down the halls of time, from the caves of our ancestors to the final confrontation under the hammer of nuclear annihilation.