I was stuck in an airport for five hours longer than expected yesterday, so didn't have this ready to go and didn't have a way to put it up.
Brian O'Nolan was an Irish civil servant who had ten siblings, all of whom he had to help support for various reasons. The Civil Service at the time (first half of the twentieth century) was that rare thing in Ireland, a job with a steady paycheck a man could live off of; but if you needed any extra money beyond that, your options were limited. It was not strictly illegal, but was very much frowned upon (as it generally is in a civil service), for a civil servant to express opinions in public on controversial matters, so if you wanted to do some writing on the side, you really needed to get departmental approval, and you can well imagine the problems you'd get trying to get anything particularly creative through the approval process of bureaucracy. O'Nolan got around this by a prolific use of pseudonyms. In many cases, that he was the author was in reality widely known, but civil servants are generally good at distinguishing what is known from what is officially known, and the pseudonyms let O'Nolan earn his much-needed extra spending money while letting his colleagues save face by not associating his real name with the satirical work at which he excelled.
And even we don't know all of his pseudonyms; there are many works that may or may not be O'Nolan's. (The problem is not made easier by the fact that one of O'Nolan's favorite things was to write crazy pseudonymous responses to irate pseudonymous letters he had written complaining about his pseudonymous columns.) The pseudonym under which he most garnered his fame was Myles na gCopaleen, which he used for satirical columns in the Irish Times; his column, "Cruiskeen Lawn", with its zany humor and endless imagination, developed an enthusiastic fan following in Ireland. (The Irish Times, aware of O'Nolan's situation, had the official position that the column had three pseudonymous authors. In reality, O'Nolan was the sole author, but it allowed the paper some wiggle room to shield O'Nolan if one of his columns touched a raw nerve in the wrong politician.) But the pseudonym that will likely last longest and the world over is Flann O'Brien, which he used for his novels.
I first read Flann O'Brien's The Third Policeman in college and it immediately became perhaps my favorite postmodern novel. He wrote it about 1939, and was himself very pleased with it, but he failed completely to find any publisher willing to publish it. Rather heartbroken about it, he withdrew the manuscript from consideration and it was only published in 1967, the year after his death. In a sense it is a fitting irony that it was only the author's death that made the book publishable, since the book, to the extent it is about anything, is about death, of all kinds. At least, it is about death and bicycles. Or rather, it is about death and bicycles and teeth and policemen and the nameless narrator's soul, which for convenience he calls 'Joe'. And, in short, omnium, which is a name the signifies both a bicycle race and any nondescript or miscellaneous whatnot.
The BBC has a very good audio abridgement of it, which you can find at the Internet Archive.