Max Lightwood is the youngest of the Lightwood family.
His first appearance is in City of Ashes, however he is known of in City of Bones, when it is revealed he and his parents are in Idris, the home land of Shadowhunters.
Currently, no-one is cast as Max.
Max is 9 years old, who is described as being skinny, with dark hair, grey eyes and glasses. When Clary first meets him, she states that he reminds her of Simon when he was her age. Jace also states that he is like a cat and can sleep anywhere and through anything.
Max is often ignored by his siblings as he is young and they do their best to try and save him, despite him wanting to constantly be of help to his family and friends.