The Invisible Host is a 1930 American mystery/thriller novel written by the husband-wife team of Gwen Bristow and Bruce Manning.

Though little remembered today, it did well enough in its own time for Hollywood to adapt it into a feature film, 1934's The Ninth Guest (which name would also be utilized for subsequent editions of the book).

It has been noted that Agatha Christie's much more famous tale, 1939's Ten Little Indians, bears striking similarities to this novel.

There is no evidence Agatha Christie saw either the play (which had a brief run on Broadway from August to October 1930[3]) or the 1934 film.

The unseen host has meticulously prepared the demise of each guest, and has booby-trapped the penthouse to prevent anyone from escaping.