 chief among them being,  of course, that David Tennant played Barty Crouch Jr. in the film of  "Harry Potter and the Goblet of Fire." Other crossover performances  include Zoe Wanamaker (the villainous trampoline Cassandra in "End  of the World" and "New Earth" and also Madam Hooch in "Harry Potter  and the Sorcerors Stone") 