June 26, 1817 - September 24, 1848: Age 31
Branwell Brontë was the male Brontë; younger brother to Maria, Elizabeth, and Charlotte (author of Jane Eyre) and older brother to Emily (author of Wuthering Heights) and Anne (author of The Tenant of Wildfell Hall). The girls were sent to a horrible sadistic boarding school (read Jane Eyre for the descriptions it inspired). Within a year the two eldest girls died "in ill-health" and the surviving three girls were sent home. Meanwhile, Branwell was being educated at home by their father. The four surviving siblings became closer than ever, developing a rich, imaginative world together.
Great things were expected of Branwell; he had a reputation in their town for being a brilliant boy. He painted and wrote poetry, and chatted with the patrons of the local pub. It was expected that he would go on to Oxford or Cambridge or some other great endeavour. He took a few art lessons, but a plan for him to attend the Royal Academy in London came to nothing. After a couple of attempts at employment, his sister Anne managed to secure him a post as tutor to the son of the family who employed her as a governess. He was dismissed from the family in 1845 under murky circumstances, which almost certainly included an affair with the boy's mother (whose name, interestingly, was Mrs Robinson).
During the next three years the three sisters were engaged in writing and publishing poetry and novels, while also trying to establish a school of their own in order to escape the need to live and work in other households as governesses, the only respectable post available for unmarried women of their class. Branwell painted and wrote poetry, but sunk deeper into depression, turning to alcohol and possibly also laudanum for solace. The portrait shown in this entry of the three Brontë sisters was painted by Branwell. He originally included himself, but later painted himself out, although his shape can clearly be seen. By the summer of 1848 it became clear that in addition to his addictions and depression he had contracted tuberculosis. On September 24, 1848 he died.
In Salmon of Doubt Douglas Adams makes the intriguing statement that Branwell "died standing up and leaning on a mantelpiece, just to prove it could be done". There is no way to consult Adams on his sources (he's dead too now) but it is mentioned in an early biography of Charlotte Bronte, "I have heard, from one who attended Branwell in his last illness, that he resolved on standing up to die. He had repeatedly said, that as long as there was life there was strength of will to do what it chose; and when the last agony came on, he insisted on assuming the position just mentioned." (Elizabeth Gaskell, The Life of Charlotte Bronte, 1857). UPDATE: I am assured by a student of things Bronte that this tidbit is not true, and I rather suspect they are right. Awaiting a confirmation of source to refute Mrs. Gaskell in a suitably scholarly manner.
His sisters Anne and Emily also contracted the disease. Emily died that December, and Anne the following May. Charlotte lived on to 1855, dying in the first trimester of pregnancy, possibly from excessive vomiting from morning sickness.
Sources: Wikipedia, Brontë Parsonage Museum