Joseph Edgar Allen John Mannix (February 25, 1891 – August 30, 1963) was an American film studio executive and producer.

He is remembered for his work as a "fixer", who was paid to cover up Hollywood stars' often colorful private lives to protect their public image and profitability for the studio.

[5][6] Mannix left MGM in August 1958, after having suffered several heart attacks, although he stayed on as adviser, particularly in the area of industrial relations.

[9] After Bernice's death, Mannix began living with actress and Ziegfeld Follies dancer Toni Lanier, with whom he had been having an affair.

[10] Mannix was suspected of involvement in the death of actor George Reeves, the star of the television series Adventures of Superman.

[15] Kashner and Schoenberger's partially fictionalized biography Hollywood Kryptonite alleged, without citing any sources, that Toni Lanier Mannix, using her husband's criminal connections, ordered George Reeves' murder.