Actually two Brendans for the price of one!
Not all that well known today - not on the American side of the Atlantic, at least - Brendan was lionized in his own time. As a young (and skinny) 16 year old, Brendan joined the Irish Republican Army, got caught during the IRA bombing campaign of 1939, and was sentenced to reform school. There he found the British and Protestant headmaster wasn't quite the ogre he expected. Alas, reform school didn't change his philosophy toward effecting change, and Brendan was later sentenced to 14 years to a real prison for attempted murder of English police officers.
With not much to do in English jails, he began writing plays and prose, and he was released after serving only four years. Although he never actually renounced his affiliation with the IRA or their tactics, he turned his attention to literature and was never really an active member after the mid-1940's.
Out of prison Brendan began submitting stories, poems, and plays to magazines and producers. His play The Quare Fellow, performed at Dublin's Pike Theater in 1954, solidified his reputation at home, and when the play was produced in England two years later, Brendan had hit the big time.
Brendan toured the world. A superb speaker and all-around character, he was particularly popular among the Irish American community which then had large contingencies in cities like Chicago and New York and who in general were sympathetic to his Irish Republican philosophy. Quickly falling victim of his own self-image and a horribly unhealthy lifestyle, plauged with diabetes and drinking heavily (never a good mix), he died at age 41 in 1964.
There are a couple of books out about Brendan that attempt at objectivity, both from around the same time.
Brendan Behan: A Life, Michael O'Sullivan, Blackwater Press, 1997. The most recent biography by a bit, it does a pretty good job at separating the Behan truth from Brendan's chaff.
Brendan Behan, Ulick O'Connor, Abacus, (1993). This book irritated the heck out of the rest of the Behan clan (Brendan's brother, Dominic, said he would take Mr. O'Connor by the scruff of the neck and sock him around London). Part of the problem was Ulick wrote of Brendan's epicenicity, although it's not all that clear whether this was a true characteristic or possibly a situational phenomenon. All in all, though, this biography seems to be generally taken as accurate.
Ulick, himself, had - indeed, still has - a reputation for being a rather boisterous gentleman, and he once nearly came to fisticuffs with Brendan over their particular political differences (Brendan even called Ulick a not very nice name). Still, Ulick was and remains a fan of and expert on Brendan and his writings. Contrasting the longevity of Ulick with the short span of Brendan, we should remember that despite both men being quite fond of the party, Ulick took his first drink at age 40 and really has never been much of an imbiber.
Borstal Boy, Brendan Behan, Hutchinson (1958). This - we must admit - novel about Brendan in reform school. Read by CooperToons too many years ago, the specifics are a bit fuzzy. As in all autobiography, take it with a grain of salt.
It took a while, but at the turn of the Millenium, Brendan's book was finally made into a movie which was neither particularly successful nor very well received.