Shields was born in New York City into a well-known American society family with links to Italian nobility. Her paternal grandmother was Princess Marina Torlonia (1916-1960), daughter of the Italian 4th Prince of Civitella-Cesi, an Italian aristocrat, and through him Brooke can claim descent from Henry IV, King of France, Lucrezia Borgia (and thus Pope Alexander VI), Charles V, Holy Roman Emperor and Honore I, Prince of Monaco, among others. Marina's brother, 5th Prince Alessandro (1911-1986) married the Infanta Beatriz of Spain (1909-2002), an aunt of King of Spain Juan Carlos de Borbón. Their granddaughter Sibilla Sandra Weiller (b. 12 Jun 1968), Brooke's second cousin, married in 1994 Prince Guillaume of Luxembourg (b. 1963), a younger brother of the reigning Grand Duke of Luxembourg. She is also the descendent of Charlemagne,Holy Roman Emperor and King of Italy ;William the Conqueror, King of England; Hugh Capet, King of France ;Ferdinand the Great, King of Castile and Leon; and D. Alfonso Henriquez, the first King of Portugal. Her father was Francis Alexander Shields, and her mother is Teri Shields (née Maria Theresa Schmonn). Shields adopted her middle name, Camille, for her Confirmation at age 10. Shields' parents divorced when she was a child, and her father later married Diana Lippert Auchincloss, the former wife of Thomas Gore Auchincloss (a half-brother of Gore Vidal and a stepbrother of Jacqueline Kennedy Onassis). The actress has three half-sisters: Marina (who married Thomas William Purcell), Olympia, and Christina Shields. She also has two stepsiblings, Diana Luise Auchincloss and Thomas Gore Auchincloss Jr. She attended the all-girl Lenox School. She graduated from Dwight-Englewood School in Englewood, New Jersey.

Her paternal grandparents were Francis Xavier Shields, a tennis star of Irish descent, and his second wife, the Italian princess Donna Marina Torlonia di Civitella-Cesi, a half-Italian, half-American socialite who was a sister of Don Alessandro Torlonia, 5th Prince di Civitella-Cesi, the husband of Infanta Beatriz of Spain (an aunt of King Juan Carlos I of Spain). Through her grandmother she is related to several Italian noble families (most notably Borgia, Medici, d'Este and di Savoia). The paternal grandmother of Shields' great-grandfather, Don Marino Torlonia (the fourth prince of Civitella-Cesi), was Princess Donna Anna Sforza-Cesarini, a descendant of Ludovico Sforza, Duke of Milan and patron of Leonardo da Vinci. Torlonia's maternal grandmother was Princess Donna Leopoldina Doria-Pamphilli-Landi, the granddaughter of Leopoldina of Savoy, a princess of the royal family of Piedmont and Sardinia, which later became the Royal Family of Italy. The descendant of many popes, Torlonia inherited the administration of the Banca Torlonia, which worked the finances of the Vatican and several other investments. He was one of the richest noblemen in Italy around the beginning of the twentieth century, and introduced the first motor car in Rome. Shields is a second cousin once removed of the actress Glenn Close. Shields's great-grandmother Mary Elsie Moore (wife of Don Marino Torlonia, 4th Prince di Civitella-Cesi) was Close's great-aunt, a sister of Close's maternal grandfather, Charles Arthur Moore.

During the 1980s and 1990s, Shields' romantic relationships were the subject of many tabloid articles. Among the celebrities she dated were Ted McGinley (her high school prom escort), Dean Cain (her Princeton roommate), John F. Kennedy Jr., Michael Bolton, Prince Albert II of Monaco, George Michael and Michael Jackson (she was his date to the 1984 Grammy Awards). Shields was married from April 19, 1997, to April 9, 1999, to professional tennis player Andre Agassi; their marriage was annulled. Since April 4, 2001, she has been married to television writer Chris Henchy. They have two daughters: Rowan Frances (b. May 15, 2003) and Grier Hammond (b. April 18, 2006). Honorary Ambassador of Peace for the Harvey Ball Foundation along with Jackie Chan, A. V. T. Shankardass, Jerry Lewis, Prince Albert of Monaco, Jack Nicklaus, Greg Norman, Phil Collins, Jimmy Buffett, Dale Earnhardt Jr., Darrell Waltrip, Heather Mills, Yoko Ono, Patch Adams, Sergei Khrushchev and Winnie Mandela.

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       - Chapter Eighteen: Indecent Exposure (2008) TV episode .... Wendy Healy
       - Chapter Seventeen: Bye, Bye Baby (2008) TV episode .... Wendy Healy
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       - The Way We Almost Weren't (2008) TV episode .... Miley's Mom
       - I Am Hannah, Hear Me Croak (2007) TV episode .... Miley's Mom
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• Bag Boy (2007) .... Mrs. Hart
  ... aka National Lampoon's Bag Boy (USA: complete title)
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       - Riddler's Revenge (2007) TV episode (voice) .... Julie
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       - That's Summer Sausage, Not Salami (2007) TV episode .... Danielle Stewert
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       - Diana Lubey (2006) TV episode .... Faith Wolper
       - Faith Wolper, PhD (2006) TV episode .... Faith Wolper
       - Cindy Plumb (2006) TV episode .... Faith Wolper
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       - Siren Call (2006) TV episode .... Kelly Sloane-Raines
• Bob the Butler (2005) .... Anne Jamieson
• New Car Smell (2005) (TV) .... April
• The Easter Egg Adventure (2004) (voice) .... Horrible Harriet Hare
• "That '70s Show" .... Pamela Burkhart (7 episodes, 2004)
       - Time Is on My Side (2004) TV episode .... Pamela Burkhart
       - Going Mobile (2004) TV episode .... Pamela Burkhart
       - The Seeker (2004) TV episode .... Pamela Burkhart
       - Squeeze Box (2004) TV episode .... Pamela Burkhart
       - Substitute (2004) TV episode .... Pamela Burkhart
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       - Finale: Part 1 (2000) TV episode .... Susan Keane
       - Finale: Part 2 (2000) TV episode .... Susan Keane
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