避役科（学名：Chamaeleonidae，英语：chameleon）俗称变色龙，是属于爬行纲的一种动物，与蜥蜴同属于蜥蜴亚目。主要分布于非洲东部与马达加斯加。

皮肤被颗粒状鳞覆盖，真皮内有多种色素细胞，能随时伸缩，变化体色；头上有钝三角形突起；双眼各自独立，可以自由转向不同视角。背部有嵴棱；四肢较长，前后肢均具5指、趾，分为相对2组，前肢内侧3指愈合，外侧2指愈合在一起，可相互握持;后肢相反，内侧2趾和外侧3趾愈合，并相对持，这样，牠就更善于在树上攀爬。

一些种类的变色龙是根据周围环境来变换体色，而另一些则是用体色来表达情绪：当受到威胁或赢得配偶时体色最为鲜艳。也有表现身体状况的颜色：发黑是身体状况差时，发白则是体温过高时。舌头较长，几乎与躯干等长，捕食时通过舌尖产生的巨大吸力吸住猎物（一说舌尖上面有黏液，捕食时，舌头能迅速「射」出，黏住昆虫）。尾较长，善于缠绕在树干上，有「第五只手」的作用。

Chameleons or chamaeleons (family Chamaeleonidae) are a distinctive and highly specialized clade of old world lizards with 202 species described as of June 2015. These species come in a range of colors, and many species have the ability to change colors. Chameleons are distinguished by their zygodactylous feet; their very long, highly modified, rapidly extrudable tongues; their swaying gait; and crests or horns on their brow and snout. Most species, the larger ones in particular, also have a prehensile tail. Chameleons' eyes are independently mobile, but in aiming at a prey item, they focus forward in coordination, affording the animal stereoscopic vision. Chameleons are adapted for climbing and visual hunting. They live in warm habitats that range from rain forest to desert conditions, various species occurring in Africa, Madagascar, southern Europe, and across southern Asia as far as Sri Lanka. They also have been introduced to Hawaii, California, and Florida, and often are kept as household pets.