Jean Kennedy Smith, who was the last surviving sibling of President John F. Kennedy and who as a U.S. ambassador played a key role in the peace process in Northern Ireland, has died, relatives said Thursday.

Smith was the eighth of nine children born to Joseph P. and Rose Kennedy, and tragically several of them preceded her in death by decades.

Her siblings included older brother Joseph Kennedy Jr., killed in action during World War II; Kathleen “Kick’ Kennedy, who died in a 1948 plane crash; the president, assassinated in 1963 and Sen. Robert F. Kennedy, slain in 1968.

Smith, who married Kennedy family financial adviser and future White House chief of staff Stephen Edward Smith in 1956, was viewed for much of her life as a quiet sister who shunned the spotlight.

The same year, she accompanied her brother — the first Irish Catholic president — on his famous visit to Ireland.