Question: De Selby is a fictional character written by which Irish writer?

full_context: Document 1: The Third Policeman: The Third Policeman is a novel by Irish writer Brian O'Nolan, writing under the pseudonym Flann O'Brien. It was written between 1939 and 1940, but after it initially failed to find a publisher, the author withdrew the manuscript from circulation and claimed he had lost it. The book remained unpublished at the time of his death in 1966. It was published by MacGibbon & Kee in 1967.
Document 2: S. (Dorst novel): S. is a 2013 novel written by Doug Dorst and conceived by J. J. Abrams. The novel is unusual in its format, presented as a story within a story. It is composed of the novel "Ship of Theseus" by a fictional author, and hand-written notes filling the book's margins as a dialogue between two college students hoping to uncover the author's mysterious identity and the novel's secret plus loose supplementary materials tucked in between pages.
Document 3: De Selby: "De Selby" (spelled "de Selby" in "The Third Policeman" and "De Selby" in "The Dalkey Archive") is a fictional character originally created by Flann O'Brien for his novel "The Third Policeman" in which the nameless narrator intends to use the proceeds of murder and robbery to publish his commentaries on de Selby — a crackpot savant who theorizes, among other things, that the earth is actually shaped like a sausage.
Document 4: Manning O'Brine: Manning O'Brine was an Irish writer of thrillers and television screenplays about whom surprisingly little is known. His date of birth is uncertain: at least one authoritative source gives it as 1915; the dust jacket of his last American publication, however, says that he was born in Connemara, Ireland, in 1913 with dual Irish and Italian citizenship. Internet booksellers frequently give his date of death as 1977. All of his novels concern espionage and/or secret agents and often feature sadistic Nazis who have survived World War II and are hunted down and killed.
Document 5: Flatland: Flatland: A Romance of Many Dimensions is a satirical novella by the English schoolmaster Edwin Abbott Abbott, first published in 1884 by Seeley & Co. of London.
Document 6: The Atheist (play): The Atheist is written by Irish born playwright, Ronan Noone. His previous plays include "The Lepers of Baile Baiste" (Critics Pick, Boston Globe) and "The Blowin of Baile Gall" which had its Off-Broadway debut, produced by Gabriel Byrne, at the Irish arts Center in New York in 2005. "The Blowin of Baile Gall" was nominated by the American Theatre Critics Association for the Steinberg New Play Award and won the Elliot Norton Award for Outstanding New Script. In 2003, Noone was chosen by Boston Magazine as the Best Young Playwright of the Year. The subject of "The Atheist" is not God, but the religion of tabloid journalism.
Document 7: John and Michael Banim bibliography: This is a bibliography of the works of John Banim and Michael Banim. Many of their works were published pseudonymously under the name "The O'Hara Family". John used the name Barnes O'Hara, while Michael used the name Abel O'Hara.
Document 8: They're a Weird Mob: They're a Weird Mob is a popular Australian comic novel written by John O'Grady under the pseudonym "Nino Culotta", the name of the main character of the book. The book was the first published novel by O'Grady, with an initial print run of 6,000 hardback copies. In less than six months, the book had been reprinted eight times and sold 74,000 copies. In the first year of publication, over 130,000 copies were sold. By the time of O'Grady's death in 1981, "They're A Weird Mob" was in its forty-seventh impression, with sales approaching the one million mark. Published by Ure Smith in 1957, the manuscript had been earlier rejected by publisher Angus & Robertson, and is reputedly the result of a ten pound bet between O'Grady and his brother, novelist Frank O'Grady.
Document 9: Brian O'Nolan: Brian O'Nolan (Irish: "Brian Ó Nualláin" ; 5 October 1911 – 1 April 1966) was an Irish novelist, playwright and satirist, considered a major figure in twentieth century Irish literature. Born in Strabane, County Tyrone, he is regarded as a key figure in postmodern literature. His English language novels, such as "At Swim-Two-Birds", and "The Third Policeman", were written under the "pen name" Flann O'Brien. His many satirical columns in "The Irish Times" and an Irish language novel "An Béal Bocht" were written under the name Myles na gCopaleen.
Document 10: Conor Cruise O'Brien: Conor Cruise O'Brien (3 November 1917 – 18 December 2008) often nicknamed "The Cruiser", was an Irish politician, writer, historian and academic. His opinion on the role of Britain in Ireland and in Northern Ireland changed during the 1970s, in response to the outbreak of The Troubles. He saw opposing nationalist and unionist traditions as irreconcilable and switched from a nationalist to a unionist view of Irish politics and history. O'Brien's outlook was always radical and the positions he took were seldom orthodox. He summarised his position as intending "to administer an electric shock to the Irish psyche".
Document 11: Foaly: Foaly is a fictional character in the Artemis Fowl series written by Eoin Colfer. He is the technical consultant to the Lower Elements Police (LEP). He is the most intelligent centaur on and under the Earth, considers himself to be an unappreciated genius, and is the inventor of most of the advanced technology possessed by the fairy world, rivaled only by Opal Koboi.
Document 12: Patrick McCabe (novelist): Patrick McCabe (born 27 March 1955) is an Irish writer. Known for his mostly dark and violent novels set in contemporary—often small-town—Ireland, McCabe has been twice shortlisted for the Booker Prize, for "The Butcher Boy" and "Breakfast on Pluto", both of which have been made into films.
Document 13: Walter Sorrells: Walter Sorrells is an award-winning author of mystery and suspense novels for adults and teens. He has written many novels, including "Fake I.D.", named one of the ten Best Mysteries by Booklist magazine in 2005 and several novels based-on the television series Flight 29 Down. He also writes under the pseudonyms Lynn Abercrombie and Ruth Birmingham. He graduated from Haverford College in 1985, where he majored in History.
Document 14: Sphereland: Sphereland: A Fantasy About Curved Spaces and an Expanding Universe is a 1965 novel by Dionys Burger, and is a sequel to "Flatland", a novel by "A Square" (a pen name of Edwin Abbott Abbott). The novel expands upon the social and mathematical foundations on which "Flatland" is based. It is markedly different from the first novel in that it has a more prosaic ending and treatment of society.
Document 15: Dirk Gently: Dirk Gently (born Svlad Cjelli, also known as Dirk Cjelli) is a fictional character created by Douglas Adams and featured in the books "Dirk Gently's Holistic Detective Agency" and "The Long Dark Tea-Time of the Soul". He is portrayed as a pudgy man who normally wears a heavy old light brown suit, red checked shirt with a green striped tie, long leather coat, red hat and thick metal-rimmed spectacles. "Dirk Gently" is not the character's real name. It is noted early on in the first book that it is a pseudonym for "Svlad Cjelli". Dirk himself states that the name has a "Scottish dagger feel" to it.
ground_truth: Brian O'Nolan