Mission to Horatius is a novel based on the American science fiction television series Star Trek: The Original Series. It was published in 1968 by Whitman, and was the first original novel based on the series; the first novel for adult audiences, Spock Must Die!, would not be published until February 1970. Mission to Horatius details the adventures of the crew of the U.S.S. Enterprise investigating where a distress signal had originated, resulting in them engaging with several different human colonies.