Who is the Black Fish ?

Brynden Tully, popularly called "the Blackfish", is a recurring character in the third and sixth seasons. He is played by Clive Russell. Ser Brynden Tully is a knight and a member of House Tully. He is the younger brother of Lord Hoster Tully, and the uncle of Catelyn, Lysa, and Edmure Tully.

Who  is  he ?

You have seen him

You might remember he shoots a flaming arrow ,  just  before the Red Wedding takes place.