Whats the relationship between John Constantine & Oliver Queen? How was it working with the Arrow cast? Matt Ryan answers these questions and more.brStephen Amell talks about working with Matt Ryan, who plays John Constantine, on Arrow!brMatt Ryan, title character in NBCs new series “Constantine,” joins Kathie Lee and Hoda to talk about his role in the show. » Subscribe to TODAY: .brMatt Ryan (John Constantine) chats at Comic Con about reading the Hellblazer comics to research his character, how his friend who owns a comic book store is .