The obvious example would be Harper Lee- “To Kill a Mockingbird” is not too shabby for one’s only novel ever. Can anyone come up with others, regardless of artistic field- film (actors, directors, what have you), music, literature, etc.
Not exactly in the above category, but James William Guercio of Chicago fame did a pretty decent job with his only work as a film director, Electra Glide in Blue starring Robert Blake- (whatever happened to old Bobby B.?)
I don’t think “F.X. Toole” (Jerold Hayden Boyd) had any other books besides “Rope Burns” Published. He died after it came out. Two of the stories formed the basis for Million Dollar Baby. An announced movie, Pound for Pound, is, I think, also based on this collection
A Simple Plan, by Scott Smith, made into the movie with Billy Bob Thornton and Bridget Fonda. One of my favorite books, and so far as I know, the only thing ol’ Scott ever wrote.
And I was going to say the only thing Charles Laughton ever directed was Night of the Hunter, but apparently he has one other (uncredited) director’s, um, credit.
Music: Blind Faith (which went to #1) Derek and the Dominoes (maybe – only one official album while they were together, but there were two live albums released after the group broke up). Kak – very nice little psychdelic pop album, but nothing else (other albums are repackagings).
Books: Walter M. Miller only had one novel, A Canticle for Lebowitz, published during his lifetime. A sequel was unfinished (though finished by Terry Bisson and published), plus he had several short stories. Russell Griffin wrote a nice little first novel called The Time-Servers, but died soon afterwards. He also had a handful of short stories published.
Movies: William “Officer Obie” Obanhein got great reviews for his performance in Alice’s Restaurant, but went back to his day job as a cop afterwards.
*Lillian Gish * directed one film, Remodeling her Husband, then went back to acting.
The Unicorns only really produced one album, although they had a couple of singles before breaking up. Similarily, Postal Service really only released Give Up, although they had some singles and almost-albums.
Of course, there is also the Sex Pistols and Nevermind the Bollocks. Another punk band, The Heartbreakers, of Richard Hell fame, only released L.A.M.F.
Another absolutely obscure one is Jackson C. Frank. An amazing '60s singer songwriter, his first album was produced by Paul Simon… and then the world never heard from him again. Somehow, nobody paid attention to him, despite his absolute amazingness. The man actually lead a hard, hard life.