Brian Thomas Smith is an American actor and comedian. He is known for playing the dim-witted but kind-hearted Zack Johnson in The Big Bang Theory for nine seasons. He has also made other TV appearances on Fear Factor, Two and a Half Men, Happy Endings, The Neighborhood, and 9-1-1: Lone Star. On the big screen, Smith starred opposite Al Pacino and Annette Bening in Dan Fogelman's directoral debut film, Danny Collins. Other films Smith has starred in include Lethal Seduction, Babysplitters, The Wedding Party, and Concrete Blondes. Edit Biography