In the booksEdit
In the A Song of Ice and Fire novels, Tycho Nestoris is described as a tall, gaunt stick of a man with long legs. He has a gaunt face with a thin rope of a beard growing from his chin which hangs down to his waist. He wears expensive robes of a sober dark purple color, trimmed with ermine fur.
Tycho was the most important of several representatives that the Iron Bank sends to Westeros, but the TV series will apparently condense all of them into the single role of Tycho. Another representative of the bank was a man named Noho Dimittis: Noho is introduced before Tycho, in the fourth novel - roughly corresponding to Season 4 of the TV series, which will cover the second half of the third novel but also introduce some elements from the fourth. In contrast, Tycho was not introduced until the fifth novel.