Madeleine L'Engle (November 29, 1918 – September 6, 2007) was an American writer best known for her Young Adult fiction, particularly the Newbery Medal-winning A Wrinkle in Time and its sequels A Wind in the Door, A Swiftly Tilting Planet, Many Waters, and An Acceptable Time. Her works reflect her strong interest in modern science. Tesseracts, for example, are featured prominently in A Wrinkle in Time, mitochondrial DNA in A Wind in the Door, and organ regeneration in The Arm of the Starfish.
Madeleine L'Engle Camp was born November 29, 1918 and named after her great-grandmother, Madeleine L'Engle, otherwise known as Mado. Her mother, a pianist, was also named Madeleine. Her father, Charles Wadsworth Camp, was a writer, a critic, and a foreign correspondent who according to his daughter suffered lung damage from exposure to mustard gas during World War I. (In a 2004 New Yorker profile of the writer, relatives of L'Engle disputed the mustard gas story, claiming instead that Camp's illness was caused by alcoholism.)
L'Engle wrote her first story at age five, and began keeping a journal at age eight. These early literary attempts did not translate into academic success at the New York City private school where she was enrolled. A shy, clumsy child, she was branded as stupid by some of her teachers. Unable to please them, she retreated into her own world of books and writing. Her parents often disagreed about how to raise her, and as a result she attended a number of boarding schools and had many governesses. They traveled frequently. At one point, the family moved to a chateau near Chamonix in the French Alps, in what Madeleine described as the hope that the cleaner air would be easier on her father's lungs. Madeleine was sent to a boarding school in Switzerland, but in 1933 the family moved to northern Florida, and she attended another boarding school, Ashley Hall, in Charleston, South Carolina. When her father died in 1935, Madeleine arrived home too late to say goodbye.
L'Engle attended Smith College from 1937 to 1941. After graduating cum laude from Smith she moved to an apartment in New York City. In 1942 she met actor Hugh Franklin when she appeared in the play The Cherry Orchard by Anton Chekhov. L'Engle married Franklin on January 26, 1946, the year after the publication of her first novel, The Small Rain. (Later she wrote of their meeting and marriage, "We met in The Cherry Orchard and were married in The Joyous Season.") The couple's first daughter, Josephine, was born in 1947.
The family moved to a 200-year-old farmhouse called Crosswicks in rural Connecticut in 1952. To replace Franklin's lost acting income, they purchased and operated a small general store, while L'Engle continued with her writing. Their son Bion was born that same year. Four years later, seven-year-old Maria, the daughter of family friends who had died, came to live with the Franklins, and they adopted her shortly thereafter. During this period, L'Engle also served as choir director of the local Congregational Church. 
In 1959 the family returned to New York City so that Hugh could resume his acting career. The move was immediately preceded by a ten-week cross-country camping trip, during which L'Engle first had the idea for her most famous novel, A Wrinkle in Time. L'Engle had completed the book by 1960, but more than two dozen publishers rejected the story before Farrar, Straus and Giroux finally published it in 1962.
In 1960 the Franklins moved to an apartment in the Cleburne Building on West End Avenue; the apartment was sold by the estate for $4 million in 2008. From 1960 to 1966 (and again in 1989 and 1990), L'Engle taught at St. Hilda's & St. Hugh's School in New York. In 1965 she became a volunteer librarian at the Cathedral of St. John the Divine, also in New York. She later served for many years as writer-in-residence at the Cathedral, generally spending her winters in New York and her summers at Crosswicks.
During the 1960s, 1970s and 1980s, L'Engle wrote dozens of books for children and adults. One of her books for adults, Two-Part Invention, was a memoir of her marriage, completed after her husband's death from cancer on September 26, 1986.
L'Engle was seriously injured in an automobile accident in 1991, but recovered well enough to visit Antarctica in 1992. Her son, Bion Franklin, died on December 17, 1999. He was forty-seven years old.
In her final years, L'Engle became unable to travel or teach, due to reduced mobility from osteoporosis, and especially after suffering a cerebral hemorrhage in 2002. She also abandoned her former schedule of speaking engagements and seminars. A few compilations of older work, some of it previously unpublished, appeared after 2001.