Conversation so far:
What was Vidal's first screenplay?
In 1958, the director William Wyler required a script doctor to rewrite the screenplay for Ben-Hur (1959).
How did Vidal become involved in Ben-Hur?
Vidal rewrote portions of the script to resolve ambiguities of character motivation.
Was his work on Ben-Hur successful for him?
In exchange for rewriting the Ben-Hur screenplay, on location in Italy, Vidal negotiated the early termination (at the two-year mark) of his four-year contract with MGM.
Where did he go after that?
Vidal occasionally returned to the movie business, and wrote historically accurate teleplays and screenplays about subjects important to him.

Question: Were any of those screenplays notable?
Self-contained rewrite: Were any of Gore Vidal's screenplays notable?