If he's not careful Harry Potter may be, er, unseated by book hero Captain Underpants. The New York Post reports that the crime-fighting bald school principal who battles talking toilets and the evil Prof. Pippy P. Poopypants has already sold 6 million copies of his exploits. Hollywood may be calling creator Dav Pilkey, 34. His four Underpants titles are now No. 3 on the Publisher's Weekly kids' series list, right behind Harry Potter and Pokémon.