The Grand Master was one of the leaders of the Sodality. He wore purple robes.
He was present during the summoning of Mastho in 1586, where he was told to eliminate all time sensitives and time channellers by 2586. After this, his Chancellor was promoted to High Executioner, and took an equal role in leading the Sodality.
When Mastho was summoned in 2586, he told the High Executioner to kill him, which she did. (PROSE: Child of Time)