David Howard Thornton is best known for his roles as Grandpa Who in the 1st- 5th national tours of “Dr. Seuss’ How the Grinch Stole Christmas: The Musical”, the voice of Shizoku and others in the video game “Invizimals: The Lost Kingdom”, The Joker in the YouTube series “Nightwing Escalation”, and Art the Clown in the film “Terrifier”.