Question: Who was the author that penned the 6th installment of a trilogy that originated on BBC Radio 4 as a comedy broadcast in 1978?
Sentence (from "The Hitchhiker's Guide to the Galaxy"): Originally a radio comedy broadcast on BBC Radio 4 in 1978, it was later adapted to other formats, including stage shows, novels, comic books, a 1981 TV series, a 1984 computer game, and 2005 feature film.
Relevant evidence: Yes