Optical toys are a broad category of toys made widely commercially available during the 19th century that engaged with users’ visual perception, producing effects such as illusions of superimposition, motion, and depth. Some examples include the kaleidoscope (1816), thaumatrope (1825), phenakistoscope (1833), zoetrope (1834), stereoscope (1838), and praxinoscope (1877). Many related optical devices were domesticated versions of public entertainments, such as peep shows, the magic lantern, dioramas, and panoramas, all scaled down for domestic entertainment. This list is representative of many common optical toys but is in no way exhaustive, as the 19th century saw the development of many related devices sold and made at home that similarly played with vision. This entry examines the history of optical toys, their popularity with children and adults ...