Stick is a Marvel Comics character that appears in Daredevil, and in The Defenders, played by Scott Glenn. He is the one who taught martial arts to Matt Murdock and Elektra Natchios, acting as a father figure to both of them. His fierce training regime and his gruff, antisocial personality is partly responsible for Matt and Elektra's ruthless and aggressive personalities. Born blind, he is a master at several different kinds of martial arts and, as his name indicates, an expert at using a staff as his weapon. This usage of a staff as his trademark weapon is what inspired Matt's usage of a billy club as a weapon in his identity of Daredevil.
