Pierce also appeared alongside Jodie Foster in "Little Man Tate", with Anthony Hopkins in Oliver Stone's "Nixon" (1995), and with Ewan McGregor in "Down With Love" (2003). He provided the voice for Doctor Doppler in Disney's 42nd animated feature, "Treasure Planet", Slim, a stick insect in Pixar's "A Bug's Life" and Abe Sapien in Guillermo del Toro's "Hellboy". In his role in "Sleepless in Seattle" (1993), Pierce played the brother of Meg Ryan's character, a professor at Johns Hopkins University. The movie was released three months before the start of "Frasier". In 2001, he starred in the cult 1981-set summer camp comedy "Wet Hot American Summer", as the befuddled astrophysicist, Prof. Henry Newman.