Alton Butterwell was a Lord of Lord Harroway's Town and head of House Butterwell. He was the master of coin during the reign of King Maegor I Targaryen.
After King Maegor exterminated House Harroway in 44 AC, he divided up the Harroway holdings among his remaining supporters. He granted Harrenhal to House Towers, but gave rule over Lord Harroway's Town to Lord Alton and the rest of the Harroway holdings to Lord Darnold Darry.
King Maegor's wars were ruinously expensive, exhausting the royal treasury. As master of coin, Alton continuously raised taxes and imposed new ones, but these measures failed to bring in sufficient revenue. Maegor than demanded a tribute of gold from the high lords. These measures only made Maegor more loathed than he already was.
The execution of Queen Alys Harroway, and soon Queen Tyanna of the Tower as well, left Maegor in need of new brides, as he had so far failed to produce an heir. Lord Alton suggested his stout, widowed sister as a match, who, while no great beauty, had given birth to seven children, her fertility being beyond doubt. King Maegor was scornful of Alton's offer, but with Alton's remark on fertility in mind, the three Black Brides wed by the king in 47 AC were proven to be fertile.