The DIB entry is thorough. It preserves what I think is a misspelling of the name of his wife, Suzanne Dechevaux-Dumesnil - see her gravestone here. It doesn't recount Deirdre Bair's claim that Beckett suffered a nervous breakdown upon his return to Paris from the Vaucluse in 1945 - indeed, this biography doesn't even appear in the list of DIB sources, which I think is a mistake, whatever its faults. It also implies that Beckett's resistance work was confined to his time in Paris, whereas it appears that he remained on active service after he fled south. It seems to believe that Kenneth Tynan's use of the sketch Breach in his revue Oh! Calcutta! was unlicensed: in fact, Beckett wrote it at Tynan's request; his objection was that, following the opening direction "an empty stage", Tynan had interpolated "with naked people". It doesn't mention the agreeable factoid that Beckett was the only Nobel laureate to have his athletic distinctions recorded in Wisden Cricketers' Almanack (he played a couple of first-class games while at Trinity College Dublin). He remained a cricket fan: friends would videotape English cricket matches and send them to him in Paris; I heard that he once took a big shine to an English cricket fan that he met in a bar, despite the fact (or perhaps because) the man had no idea who Beckett was.
An uncle of Sam's, Jim Beckett, is also listed. Like his nephew, he was a keen athlete; a swimming Olympian and member of the national water polo team and keen on athletics, hockey, rugby, tennis and boxing. He suffered from diabetes, which led to the amputation of his legs; the DIB suggests Sam's "obsession with infirmity and limbless bodies" may have been related to his uncle's experience.
A friend of my father, Reena McDermott, grew up in the Crumlin council estate in Dublin, where a neighbor was Kathleen Behan. (Mrs. Behan's Crumlin home was known as "Kremlin" to the local wags.) Her brother, Peadar Kearney, had co-composed and written the original English lyrics for Amhrán na bhFiann, which became the Irish national anthem. According to Reena, Mrs B would offer sixpence to any child who could recite the whole thing. (Kearney's English song was later translated into Irish - not by him - and this version became the official anthem. I learned it at school first in English and the Irish version only later: it appears that these days children are taught just the Irish words.). They were quite a family: including Kearney, there are 6 of them in the DIB: Kathleen, her three sons Brendan, Dominic and Brian, and Brian's long-suffering wife Beatrice, an artist in her own right. Brendan was the star, of course, albeit one that has waned somewhat since his days of fame and notoriety in the late 1950s and 1960s of which the photo, with the comedian Jackie Gleason, is a mild example. The facts are well-known: he joined the republican movement at the age of 8, was caught in England at 16 with explosives and sent to Borstal (juvenile detention). Back in Ireland, he was arrested for shooting at policemen and sentenced to 14 years in prison. He was 19. He started writing in jail, and when he was released in a general amnesty after serving less than 5 years, began to write poetry in Irish and short stories in English. His first produced play, The Quare Fellow, was produced in Dublin and then in London, where it was a hit and later made into a film. The effect of success on Behan was not a happy one. He already had a weakness for the drink and there were plenty, particularly in Britain and the USA, who were happy to egg on a garulous and bibulous Irishman to greater stereotypical outrages. His next play, The Hostage (originally written in Irish) was another hit, to be followed by what the DIB calls his "masterpiece", his memoir Borstal Boy, which he had been working on since his time in prison.
My mother couldn't stand him. This was principally because of the time, shortly after my parent's marriage, that he turned up at their flat in Wellington Lane, Dublin in the small hours of the morning, drunk. He hammered at the door and shouted loudly, insisting on being let in. Although my parents knew him slightly - everybody in Dublin's small bohemia knew each other slightly at that time - it turned out that he was at the house because some IRA friends of his used to live there. Later, my father discovered some nasty anti-Semitic leaflets that had been left behind: during the Second World War, there were a few IRA types whose support of Nazi Germany was more than merely tactical. He had another run-in with family friend, Anna Gallagher (wife of the journalist J.P. Gallagher), a catholic from Belfast. Drunk (of course), he ripped into her as a "Scotch hoor". "I'm NOT Scotch!!" came the indignant reply.
All of this is so much folderol, of course. He was a fine writer and his best work still holds up. I recently saw the movie adaptation of The Quare Fellow, which was not much liked at the time, principally because of the liberties it took with Behan's play. It's a very good film, and you can see the best of Behan in it. His brother Dominic wrote some great folk songs, notably The Auld Triangle (sometime attributed to Brendan, since it featured in The Quare Fellow), sung here by the great Luke Kelly, The Patriot Game and Liverpool Lou. A third brother, Brian, was also a writer. He was a political activist in England and was expelled from the Socialist Labour League by fellow-Irishman Gerry Healy (I"m disappointed to see that Healy doesn't rate an entry in the DIB: he's in the British DNB).