She was married three times. Her husbands were:
- Aristotle Onassis (28 December 1946 – 1960); with him she had two children, Alexander Onassis (1948–1973) and Christina Onassis (1950–1988). She divorced him upon her discovering that he was having an affair with the opera singer Maria Callas.[1]
- John Spencer-Churchill, Marquess of Blandford (23 October 1961 – March 1971), later 11th Duke of Marlborough.
- Stavros Niarchos (21 October 1971 – 1974), her sister Eugenia's widower.
After her divorce from Aristotle Onassis, she resumed using her maiden name, Livanos, until her marriage to Spencer-Churchill.
Her son with Onassis, Alexander Onassis, died at the age of 24 in January 1973, as a result of injuries sustained during an airplane crash in Athens.[2]
Athina Niarchos died on 10 October 1974 in the Hôtel de Chanaleilles, the Parisian mansion that she shared with her husband. Her death was officially ruled by pathologists as having resulted from an acute edema of the lung, but has also been attributed to her suffering a drug overdose.[3][4] She was buried next to her sister at the Bois-de-Vaux Cemetery in Lausanne, Switzerland.
Her daughter, Christina Onassis, sued Stavros Niarchos, her mother's widower, for her mother's estimated US$250 million (in 1974 dollars) estate, claiming the marriage should be annulled by Greek law. Christina later ended the lawsuit and Niarchos returned all of his wife's money as well as her jewelry, artwork and other personal effects to Christina.
Her only living descendant is her namesake granddaughter, Athina Onassis, Christina's daughter.