Lucius Fox is a character in Joker II- Arkham Knight and Joker III- Fall to Insanity. He is portrayed by Reg E. Cathey.
Lucius Fox was the best friend of Thomas Wayne and had always had a stable position at Wayne Enterprises. Lucius designed various tech for the US military and modified much of it for Bruce Wayne's career as The Batman- Lucius knowing his secret identity. Danger knocked on Lucius' door when the Joker surfaced after his breakout from Arkham.