(October 20, 1968 - March 15, 1975) (his death)
After Robert Kennedy's death, Kennedy reportedly suffered a relapse of the depression she had experienced in the days following her husband's assassination nearly five years prior. She came to fear for her life and those of her children, saying: "If they're killing Kennedy's, then my children are targets ... I want to get out of this country".
On October 20, 1968, Kennedy married her long-time friend Aristotle Onassis, a wealthy Greek shipping magnate who was able to provide the privacy and security she sought for herself and her children. The wedding took place on Skorpios, Onassis's private Greek island in the Ionian Sea. Following her second marriage, she was now using the legal name Jacqueline Onassis and subsequently lost her right to Secret Service protection, which was an entitlement to a widow of a U.S. president. The marriage brought her considerable adverse publicity. The fact that Aristotle was divorced and his ex-wife was still living led to speculation that Jacqueline might be excommunicated by the Roman Catholic church, though that idea was explicitly dismissed by Boston's Archbishop, Cardinal Richard Cushing as "nonsense." She was condemned as a "public sinner," and became the target of paparazzi who followed her everywhere and nicknamed her "Jackie O".
During their marriage, the couple inhabited six different residences: her 15-room Fifth Avenue apartment in Manhattan, her horse farm in New Jersey, his Avenue Foch apartment in Paris, his private island Skorpios, his house in Athens, and his 325 ft (99 m) yacht Christina O. Kennedy ensured that her children continued a connection with the Kennedy family by having Ted Kennedy visit them often. She developed a close relationship with Ted, and he was involved in her public appearances from then on.
Aristotle Onassis' health began deteriorating rapidly following the death of his son Alexander in a plane crash in 1973, and he died of respiratory failure at age 69 in Paris on March 15, 1975. His financial legacy was severely limited under Greek law, which dictated how much a non-Greek surviving spouse could inherit. After two years of legal wrangling, Kennedy eventually accepted a settlement of $26 million from Christina Onassis—Aristotle's daughter and sole heir— and waived all other claims to the Onassis estate.