She first came to the public eye during her time at the Brearley School in New York City between 1940 and 1942, when she was photographed attending fashionable nightclubs with her friends Carol Marcus and Gloria Vanderbilt.

The 36-year age gap between them caused a scandal and severed O'Neill's relationship with her father, who was only six months older than Chaplin and who had already strongly disapproved of her wish to become an actress.

The first decade of their marriage was spent living in Beverly Hills, but after Chaplin's reentry permit to the United States was cancelled during a voyage to London in 1952, they moved to Manoir de Ban in the Swiss village of Corsier-sur-Vevey.

Oona O'Neill was born on 14 May 1925 in the British colony of Bermuda, where her parents had relocated six months before her birth in the hopes that it would be a good place to write during the winter.

[4][note 1] Her parents' marriage had been for a long time strained by Eugene's alcoholism, and started to disintegrate after he had an affair with actress Carlotta Monterey while they were living in Belgrade, Maine, in the summer of 1926.

[7] After the divorce, O'Neill's childhood was mostly spent living with her mother and brother in West Point Pleasant and occasionally at Spithead, in which Agnes had a lifetime interest.

[18][note 3] After graduating from Brearley, O'Neill declined an offer for a place to study at Vassar College and instead chose to pursue an acting career, despite her father's resistance.

[23] During the trip, O'Neill briefly appeared in a production of Saroyan's play, The Time of Your Life, in San Francisco and unsuccessfully attempted to meet her father, who was living nearby.

[27] Crocker photographed the event for gossip columnist Louella Parsons, to whom Chaplin had given exclusive rights to publicize news of the marriage in the hopes that she would write a more positive article about it than her rival, Hedda Hopper, who strongly disliked him.

[27] The elopement received a large amount of media attention due to the 36-year age gap between O'Neill and Chaplin and because his ex-girlfriend, Joan Barry, had filed a paternity suit against him only two weeks earlier.

Although Agnes had given the union her blessing, it cemented O'Neill's estrangement from her father, who disowned her and her issue and refused all future attempts of reconciliation.

[33] In September 1952, while travelling with O'Neill and their children to London for the premiere of Limelight on board the ocean liner Queen Elizabeth, his re-entry permit was revoked.

[34] The family soon decided to move permanently to Europe, and in November 1952, O'Neill flew back to the US to transfer Chaplin's assets to European bank accounts and to close up their house and the studio.

Chaplin's coffin was stolen from his grave by two unemployed mechanics, Roman Wardas and Gantcho Ganev, who unsuccessfully demanded a ransom from O'Neill in exchange for the body.

[38] The pair were caught in a large police operation two months later, and Chaplin's unopened coffin was reinterred, having been found buried in a field in the nearby village of Noville.

[40] According to unofficial biographer Jane Scovell and ex-daughter-in-law Patrice Chaplin, O'Neill was an alcoholic and became almost a recluse after returning permanently to Manoir de Ban in the late 1980s.