Sibon nebulatus, commonly known as the clouded snake, is a species of small, slender arboreal snake which is found in southern Mexico, Central America, northern South America, Isla Margarita, and Trinidad and Tobago. The body colour of S. nebulatus varies from grey to brown with dark brown irregular ring-like crossbands. These crossbands are edged by fine, irregular, beige spots. The belly ranges from white to beige, speckled with tiny dark brown points. The labial scale on the upper lip behind the eye is enlarged.