Orn "Blackfoot" Finch was a prisoner in the Iron Stocks who was freed by Grog. As an NPC, Orn was played by Matthew Mercer.
He has the appearance of a lowly beggar with long hair wearing tattered clothes. His feet are bare and blackened.
"In the Belly of the Beast" (1x54)
Orn was freed from his imprisonment by Grog.