C. S. Lewis was born in Belfast, Ireland, on November 29, 1898, to Albert J. Lewis and Florence Augusta Hamilton Lewis. Throughout his life, Lewis was known to his family and friends as "Jack"—a nickname he coined for himself at the age of four after the beloved neighborhood dog Jacksie died. Lewis had one brother, Warren Hamilton Lewis (1895–1973). Lewis's mother died of cancer in 1908 when he was just nine years old.
Lewis went on to receive a scholarship to University College, Oxford, in 1916. Lewis took a hiatus from study after the outbreak of WWI, enlisting in the British Army in 1917. On April 15, 1918, Lewis was wounded in the Battle of Arras and was discharged a little more than a year later in December 1919.
While in the army, Lewis became close friends with his roommate Paddy Moore. Moore was killed in battle in 1918. After Lewis was discharged, he followed through with a promise to his friend to look after Moore's family. Lewis moved in with Paddy's mother, Jane Moore, and her daughter, Maureen, in 1920. The three of them eventually moved into "The Kilns," which they purchased jointly along with Lewis's older brother, Warren.
On May 20, 1925, Lewis was appointed Fellow and Tutor in English Literature at Oxford University, where he served for twenty-nine years until 1954.
During his time at Oxford, Lewis went from being an atheist to being one of the most influential Christian writers of the 20th century; 1931 marks the year of Lewis's conversion to Christianity. He became a member of the Church of England. Lewis cites his friendship with J. R. R. Tolkien, as well as the writings of the converted G. K. Chesterton, as influencing his conversion.
Lewis was married late in life at age fifty-eight to Joy Davidman Gresham, an American writer fifteen years his junior. They married in 1956, two years after Lewis accepted the chair of Medieval and Renaissance Literature at Cambridge, where he finished out his career.
After a four-year fight with bone cancer, Joy passed away in 1960. Lewis continued to care for her two sons, Douglas and David Gresham.
C. S. Lewis died at his home "The Kilns" on November 22, 1963. His grave is in the yard of Holy Trinity Church in Headington Quarry, Oxford. Warren Lewis died on Monday, April 9, 1973. Their names are on a single stone bearing the inscription "Men must endure their going hence."
(taken from http://www.cslewis.com/about.aspx)