Mr. Hartwell

John Barlow first appears in the Pilot of 666 Park Avenue.

Story
Mr. Hartwell is apparently a famous violinist who only got his success after making a deal with Gavin Doran. In the Pilot, he tries to flee the Drake after a performance that causes his hands to bleed.

His contract apparently expired and he is seen begging Gavin for more time who refuses to give him any more. As Mr. Hartwell tries to flee the Drake, he gets sucked into the doors of the old building and is presumably killed.