O ator que interpretou Jon "Greatjon" Umber, Clive Mantle não pôde fazer as temporadas 2 e 3 devido a agendamento de conflitos , e é por isso que ele desapareceu do programa de TV.
Nos livros:
he was at the Red Wedding, survived and was a captive of the Freys. He is mentioned somewhat in A Feast for Crows and A Dance with Dragons, there is detail on his wikia page if you want it.