Maelys the Monstrous

The last scion, by the male line, of the Blackfyres. Born with a vestigial twin (rumored to have eaten it at the womb), was the last who wielded the sword Blackfyre, that heirloom of the Targaryen dinasty, and the last of his family to command the Golden Company, founded by Aegor Bittersteel, brother to Daemon Blackfyre. He was also the last who claimed the Iron Throne, at the Ninepenny Kings War, to be slayed by a young Ser Barristan Selmy of the Kingsguard. That is how I imagine the last descendant of Daemon, the Great Bastard, and the Blackfyre sword.