Although the main characters of The Big Bang Theory would initially appear to possess nearly encyclopedic knowledge of comic books, they've actually made significant mistakes that lend credit to one of the series' greatest criticisms. From the pilot to The Big Bang Theory series finale, Leonard (Johnny Galecki) and his friends express constant love for the caped heroes of the DC universe. All 12 seasons of The Big Bang Theory include countless superhero references, especially after Stuart's (Kevin Sussman) introduction in season 2 made the comic book store a more regular set piece.