Olivia Catherine Hack is an American actress, best known for providing the voice of Rhonda Wellington Lloyd in Nickelodeon's Hey Arnold!, and for playing Cindy Brady in the 1990s theatrical Brady Bunch films. She has also done voice work for Fillmore!, Bratz as Cloe, Family Guy, Blood+ and Avatar: The Last Airbender as Ty Lee. She appeared in Star Trek Generations, Party of Five and Gilmore Girls.