Sir Arthur Conan Doyle was a Human writer. Living in 19th century England, he wrote the famous Sherlock Holmes books and short stories. He created the character of Professor Moriarty as a worthy adversary of Holmes. (TNG: "Elementary, Dear Data", "Ship in a Bottle")
Captain Spock once implied that he was a descendant of Doyle's – "An ancestor of mine maintained, that if you eliminate the impossible, whatever remains, however improbable, must be the truth." (Star Trek VI: The Undiscovered Country)
Background information Edit
Star Trek VI: The Undiscovered Country director and screenplay writer Nicholas Meyer had previously written the screenplay for The Seven-Per-Cent Solution, based on his novel. The film and book feature Sherlock Holmes, Arthur Conan Doyle's creation. This may be the reason that Spock implies that he is a descendant of Doyle's through his mother Amanda Grayson.
Although Professor Moriarty described Conan Doyle as an Englishman in "Ship in a Bottle", he was in fact Scottish.
A. Conan Doyle received credit as the Sherlock Holmes characters creator in the end credits of the TNG Season 6 episode "Ship in a Bottle". It was also mentioned that this use was arranged with Dame Jean Conan Doyle.