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!, was not 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.