Gilbert Keith Chesterton KC*SG (29 May 1874 – 14 June 1936) was an English author, philosopher, Christian apologist, poet, journalist and magazine editor, and literary and art critic. Chesterton's wit, paradoxical style, and defence of tradition made him a dominant figure in early 20th-century literature.

Chesterton created the fictional priest-detective Father Brown, and wrote on apologetics, such as his works Orthodoxy and The Everlasting Man. Chesterton routinely referred to himself as an orthodox Christian and came to identify this position more and more with Catholicism, eventually converting from high church Anglicanism. Biographers have identified him as a successor to such Victorian authors as Matthew Arnold, Thomas Carlyle, John Henry Newman and John Ruskin.

He has been referred to as the "prince of paradox". Of his writing style, Time observes: "Whenever possible, Chesterton made his points with popular sayings, proverbs, allegories—first carefully turning them inside out." His writings were an influence on Jorge Luis Borges, who compared his work with that of Edgar Allan Poe.

Initially educated in art, Chesterton became a prolific author, producing around 80 books, 200 short stories, 4,000 essays, and notable works such as The Man Who Was Thursday, and the Father Brown detective stories. Raised in a loosely Unitarian family, he converted to Catholicism in 1922 under his wife Frances's influence, shaping much of his later writing. A charismatic public intellectual, he debated figures like George Bernard Shaw and H. G. Wells, opposed imperialism and eugenics, and promoted distributism—a "third way" between capitalism and socialism. He died in 1936, leaving a vast and enduring legacy, with his possible sainthood still periodically discussed.

Chesterton was born in Campden Hill in Kensington, London, on 29 May 1874. His father was Edward Chesterton, an estate agent, and his mother was Marie Louise, née Grosjean, of Swiss-French origin. Chesterton was baptised at the age of one month into the Church of England, though his family were irregularly practising Unitarians. According to his autobiography, as a young man he became fascinated with the occult and, along with his brother Cecil, experimented with Ouija boards. He was educated at St Paul's School, then attended the Slade School of Art to become an illustrator. The Slade is a department of University College London, where Chesterton also took classes in literature, but he did not complete a degree in either subject. He married Frances Blogg in 1901; the marriage lasted the rest of his life. Chesterton credited Frances with leading him back to Anglicanism, though he later considered Anglicanism to be a "pale imitation". He entered in full communion with the Catholic Church in 1922. The couple were unable to have children.

A friend from schooldays was Edmund Clerihew Bentley, inventor of the clerihew, a whimsical four-line biographical poem. Chesterton wrote clerihews and illustrated his friend's first published collection of poetry, Biography for Beginners (1905), which popularised the clerihew form. He became godfather to Bentley's son Nicolas and opened his novel The Man Who Was Thursday with a poem written to Bentley.^{[citation needed]}

In September 1895, Chesterton began working for the London publisher George Redway, where he remained for just over a year. In October 1896, he moved to the publishing house T. Fisher Unwin, where he remained until 1902. During this period he undertook his first journalistic work as a freelance art and literary critic. In 1902, The Daily News gave him a weekly opinion column, followed in 1905 by a weekly column in The Illustrated London News, for which he continued to write for the next 30 years.

Early on Chesterton showed a great interest in and talent for art. He had planned to become an artist, and his writing shows a vision that clothed abstract ideas in concrete and memorable images. Father Brown is perpetually correcting the incorrect vision of the bewildered folk at the scene of the crime and wandering off at the end with the criminal to exercise his priestly role of recognition, repentance and reconciliation. For example, in the story "The Flying Stars", Father Brown entreats the character Flambeau to give up his life of crime: "There is still youth and honour and humour in you; don't fancy they will last in that trade. Men may keep a sort of level of good, but no man has ever been able to keep on one level of evil. That road goes down and down. The kind man drinks and turns cruel; the frank man kills and lies about it. Many a man I've known started like you to be an honest outlaw, a merry robber of the rich, and ended stamped into slime."