The Fraser-Wilcox illusion is one of the anomalous motion illusions observed in a stationary image, and its extension, including “rotating snakes,” which has been used extensively via the Internet, are reviewed in this chapter. Perceptual dimorphism featuring the Fraser-Wilcox illusion is explained by an interaction between two different illusions. Darkening disambiguation of the Fraser-Wilcox illusion, perceptual dimorphism, the optimized Fraser-Wilcox illusions, the effect of age on the illusion magnitude, as well as the role of color including color enhancement are demonstrated and discussed. The timing-difference model and the eye-movement model are also explored. Recent studies that relate to these concepts are also examined.