Rossart

Rossart is an unseen character in Game of Thrones. He is dead by the time of the series and only appears in the Complete Guide to Westeros. He was a Wisdom of the Alchemists' Guild.

Background
Wisdom Hallyne was a loyal servant of King Aerys II Targaryen, during whose reign the Guild rose again to royal favor. Rossart burned Aerys' enemies alive in the Red Keep's Great Hall. During the War of the Usurper, he rose to Hand of the King.

In the books
In the A Song of Ice and Fire novels, Wisdom Rossart was the head of the Alchemist's Guild during the reign of Mad King Aerys. He was the pyromancer who had cooked Lord Rickard Stark in his armor and one. After Lord Qarlton Chelsted was burned alive, Aerys made Rossart Hand of the King, choosing a burning torch as his personal sigil. He was killed by Ser Jaime Lannister during the Sack of King's Landing.