Vesemir

Vesemir is the eldest known witcher, possibly older than Kaer Morhen itself. A fighting master, knowledgable about monsters. He taught Ciri about them. For Geralt, he is a father figure (though not a biological father) and one of the closest people.

Movie and TV series
In The Hexer movie and TV series Vesemir was portrayed by Jerzy Nowak.