Justin Michael Cornwell is an American actor, writer and musician best known for playing Young Jeronicus Jangle in the Netflix original movie Jingle Jangle, Marcus Hargreeves in The Umbrella Academy and Kyle Craig in the CBS crime drama, Training Day, based on the 2001 film of the same name.

Training Day is an American crime-thriller television series that aired on CBS from February 2 to May 20, 2017. The series serves as a follow-up to the 2001 film of the same name. It stars Bill Paxton and Justin Cornwell, and is known for being one of Paxton's final performances prior to his death in February 2017.