Never worked with Alfred Hitchcock.

Hitchcock worked with so many stars in the 50s & 60s. Audrey Hepburn was one of the big ones at the time yet they never worked together.

I googled it and sure enough they nearly did;

No Bail for the Judge was to be an adaptation of a thriller novel by Henry Cecil about a female barrister who, with the assistance of a gentleman thief, has to defend her father, a High Court judge, when he is accused of murdering a prostitute. In a change of pace from Hitchcock's usual blonde actresses, Audrey Hepburn would have played the barrister, with Laurence Harvey as the thief, and John Williams as the Hepburn character's father. Some sources, including "Writing with Hitchcock" author Steven DeRosa, say that Hitchcock's interest in the novel started in the summer of 1954 while filming To Catch a Thief, and that Hitchcock hoped to have John Michael Hayes write the screenplay. Hepburn was an admirer of Hitchcock's work and had long wanted to appear one of his films.

Samuel A. Taylor, scenarist for Vertigo and Topaz, wrote the screenplay after Ernest Lehman had rejected it. The Taylor screenplay included a scene, not in the original novel, where the heroine disguises herself as a prostitute and has to fend off a rapist. Hepburn left the film, partly because of the near-rape scene, but primarily due to a pregnancy. (Hepburn suffered a miscarriage during the filming of the 1960 film The Unforgiven then gave birth to son Sean Ferrer in July 1960.) Laurence Harvey still ended up working with Hitchcock in 1959, however, on an episode that Hitchcock directed of Alfred Hitchcock Presents.

Without Hepburn, the project didn't have the same appeal for Hitchcock. Changes in British law concerning prostitution and entrapment — which took place after the novel was published — made some aspects of the screenplay implausible. Hitchcock told Paramount Pictures it was better to write off the $200,000 already spent on the film's development than to spend another $3 million for a film he no longer cared for. In the fall of 1959, a Paramount publicity brochure titled "Success in the Sixties!" had touted No Bail for the Judge as an upcoming feature film starring Hepburn, to be filmed in Technicolor and VistaVision.