A know-it-all or besserwisser (from German) is a person who appears to offer expert opinion, without possessing it.
Know-it-all or know-all may also refer to:
Books The Know-It-All, a 2004 book by A.J. Jacobs "Doctor Know-all", a German fairy tale Film and TV "Know All", an episode of Round the Twist, an Australian children's TV series Knowitalls, a 2009 British quiz show Mister Know-It-All, an American animated web series Mr. Know-It-All, a segment of the American Rocky and Bullwinkle TV cartoon Music Know-It-All (album), a 2015 album by Alessia Cara "Mr. Know It All", a 2011 single by Kelly Clarkson "He's Misstra Know-It-All", a 1974 Stevie Wonder song
See also Canada's Greatest Know-It-All, a 2012 Canadian reality television series Like You Know It All, a 2009 South Korean comedy-drama Please Kill Mr. Know It All, a 2013 Canadian romantic comedy film