Jacqueline Lee Kennedy Onassis (ne Bouvier ; July 28, 1929 May 19, 1994) was an American socialite, writer, photographer, and book editor who served as first lady of the United States from 1961 to 1963, as the wife of President John F. Kennedy. A popular first lady, she endeared the American public with her fashion sense, devotion to her family, and dedication to the historic preservation of the White House. During her lifetime, she was regarded as an international fashion icon.After graduating with a Bachelor of Arts in French literature from George Washington University in 1951, Bouvier started working for the Washington Times-Herald as an inquiring photographer. The following year, she met then-Congressman John Kennedy at a dinner party in Washington. He was elected to the Senate that same year, and the couple married on September 12, 1953, in Newport, Rhode Island. They had four children, two of whom died in infancy. Following her husband's election to the presidency in 1960, Kennedy was known for her highly publicized restoration of the White House and emphasis on arts and culture, as well as for her style. At age 31, she was the third-youngest first lady of the United States when her husband was inaugurated.

After the assassination and funeral of her husband in 1963, Kennedy and her children largely withdrew from public view. In 1968, she married Greek shipping magnate Aristotle Onassis, which caused controversy. Following Onassis's death in 1975, she had a career as a book editor in New York City, first at Viking Press and then at Doubleday, and worked to restore her public image. Even after her death, she ranks as one of the most popular and recognizable first ladies in American history, and in 1999, she was listed as one of Gallup's Most-Admired Men and Women of the 20th century. She died in 1994 and was buried at Arlington National Cemetery alongside President Kennedy.

The first lady of the United States (FLOTUS) is the title held by the hostess of the White House, usually the wife of the president of the United States, concurrent with the president's term in office. Although the first lady's role has never been codified or officially defined, she figures prominently in the political and social life of the United States. Since the early 20th century, the first lady has been assisted by official staff, now known as the Office of the First Lady and headquartered in the East Wing of the White House.

Jill Biden is the current first lady of the United States, as wife of the 46th president of the United States, Joe Biden.

While the title was not in general use until much later, Martha Washington, the wife of George Washington, the first U.S. president (1789–1797), is considered to be the inaugural first lady of the United States. During her lifetime, she was often referred to as "Lady Washington".Since the 1790s, the role of first lady has changed considerably. It has come to include involvement in political campaigns, management of the White House, championship of social causes, and representation of the president at official and ceremonial occasions. As first ladies now typically publish their memoirs, which are viewed as potential sources of additional information about their husbands' administrations, and because the public is interested in these increasingly independent women in their own right, first ladies frequently remain a focus of attention long after their husbands' terms of office have ended. Additionally, over the years individual first ladies have held influence in a range of sectors, from fashion to public opinion on policy. Historically, should a president be unmarried or a widower the president usually asks a relative to act as White House hostess.