In 1976, he was cast in Star Wars, which was shooting at Elstree Studios, Borehamwood. He appeared as Grand Moff Tarkin, despite having originally been considered for the role of Obi-Wan Kenobi. Cushing found accepting the role in a science fiction fantasy easy. "My criterion for accepting a role isn't based on what I would like to do. I try to consider what the audience would like to see me do and I thought kids would adore Star Wars."[this quote needs a citation]
During production Cushing was presented with ill-fitting riding boots for the role and they pinched his feet so much that he was given permission by George Lucas to play the role wearing his slippers. The camera operators filmed him above the knees or standing behind the table of the conference room set.
For Star Wars Episode III: Revenge of the Sith, Lucas wanted Cushing, by then deceased, to reprise his role as Tarkin through the use of archive footage and digital technology, but poor film quality made this impossible. Additionally, the scene required a full-body appearance of Tarkin, which was unavailable because of Cushing's use of slippers instead of boots when performing. Instead, Wayne Pygram took the role. Pygram was cast because it was felt he strongly resembled Cushing, but even so, he underwent extensive prosthetic makeup for his brief cameo.