Willy Wonka is not a cuddly character. He callously watches as one kid nearly drowns in a chocolate river, shrugs when one turns into a blueberry, yawns as another death-drops into a furnace, and all but encourages the last child to shrink himself to the size of a mouse. He also owns slaves.
Amidst all that horror, however, the most terrifying scene in the film is when he takes a group of children and their guardians on an acid trip through hell on his riverboat. A true monster.