Owen Vaccaro as Lewis Barnavelt, Jonathan’s 10-year old nephew Jack Black as Jonathan Barnavelt, Lewis’s uncle Cate Blanchett as Mrs. Zimmerman, a witch and Jonathan's neighbour and best friend. Kyle MacLachlan as Isaac Izard, the sinister original owner of the house. Colleen Camp as Mrs. Hanchett, a nosey, irritated neighbor of Jonathan Barnavelt.