Rainier III (Rainier Louis Henri Maxence Bertrand Grimaldi; 31 May 1923 6 April 2005) was Prince of Monaco from 1949 to his death in 2005. Rainier ruled the Principality of Monaco for almost 56 years, making him one of the longest-ruling monarchs in European history.

Rainier was born at the Prince's Palace of Monaco, the only son of Prince Pierre and Princess Charlotte of Monaco. He was crucially responsible for the transformation of Monaco's economy, shifting from its traditional casino gambling base to its current status as a tax haven and cultural destination. The Prince also coordinated the substantial reforms of Monaco's constitution, which limited the powers of sovereign rule.

Rainier married American film star Grace Kelly in 1956, which generated global media attention. They had three children: Caroline, Albert and Stphanie. He died in April 2005 from complications relating to a lung infection as a result of frequent smoking; he was succeeded by his son, Albert.

Grace Patricia Kelly (November 12, 1929 – September 14, 1982) was an American actress who, after starring in several significant films in the early to mid-1950s, became Princess of Monaco by marrying Prince Rainier III in April 1956.

Kelly was born into a well-known Catholic family of Irish and German origin in the U.S. city of Philadelphia. After graduating from the American Academy of Dramatic Arts in 1949, Kelly began appearing in New York City theatrical productions and over 40 live drama productions broadcast in early 1950s Golden Age of Television. She gained stardom from her performance in John Ford's adventure-romance Mogambo (1953), for which she was nominated for an Academy Award for Best Supporting Actress. She won the Academy Award for Best Actress for her performance in the drama The Country Girl (1954). Other notable works include the western High Noon (1952), the romantic comedy High Society (1956), and three consecutive Alfred Hitchcock suspense thrillers: Dial M for Murder (1954), Rear Window (1954), and To Catch a Thief (1955). Kelly worked with some of the most prominent leading men of the era, including Gary Cooper, Clark Gable, Ray Milland, James Stewart, Bing Crosby, William Holden, Cary Grant, Alec Guinness, and Frank Sinatra.

Kelly retired from acting at age 26 to marry Rainier, and began her duties as Princess of Monaco. Hitchcock hoped that she would appear in more of his films that required an "icy blonde" lead actress, but he was unable to coax her out of retirement. The Prince and Princess had three children: Princess Caroline, Prince Albert, and Princess Stéphanie. Kelly retained her link to America by her dual U.S. and Monégasque citizenship. Her charity work focused on young children and the arts, establishing the Princess Grace Foundation to support local artisans in 1964. Her organization for children's rights, AMADE Mondiale, gained consultive status within UNICEF and UNESCO. Her final film contribution was in 1977 to the documentary The Children of Theatre Street directed by Robert Dornhelm, where she served as the narrator. The documentary was nominated for an Academy Award for Best Documentary Feature.

Kelly died at the age of 52 at Monaco Hospital on September 14, 1982, from injuries sustained in a car crash the previous day. She is listed 13th among the American Film Institute's 25 Greatest Female Stars of Classical Hollywood Cinema. Her son, Prince Albert, helped establish the Princess Grace Awards in 1984 to recognize emerging performers in film, theatre, and dance.