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 Rossart 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 Great Hall of the Red Keep. During the War of the Usurper, he rose to Hand of the King. He died during the Sack of King's Landing.

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 elevated largely because he shared the king's passion for fire .He was the pyromancer who had cooked Lord Rickard Stark in his armor with wildfire. After Lord Qarlton Chelsted was burned alive under the Mad King's orders, Rossart became the new Hand of the King, choosing a burning torch as his personal sigil. Rossart served as Hand for less than a fortnight, before being killed during the Sack of King's Landing. Many people who weren't in the capital at the time don't even remember that he was briefly Hand of the King.