O'Brien influenced the science fiction writer and conspiracy theory satirist Robert Anton Wilson, who has O'Brien's character De Selby, an obscure intellectual in "The Third Policeman" and "The Dalkey Archive", appear in his own "The Widow's Son". In both "The Third Policeman" and "The Widow's Son", De Selby is the subject of long pseudo-scholarly footnotes. This is fitting, because O'Brien himself made free use of characters invented by other writers, claiming that there were too many fictional characters as is. O'Brien was also known for pulling the reader's leg by concocting elaborate conspiracy theories.