蜥类（Sauria）是个爬行动物演化支，包含所有现存双孔亚纲与鸟类，以及牠们的最近共同祖先、其最近共同祖先的后代。牠们最早出现于二叠纪，当时是外表类似蜥蜴的爬行动物。根据头颅骨与骨骼特征，可以进一步分为鳞龙形下纲、主龙形下纲。

在早期的非正式用法中，「Sauria」是蜥蜴亚目（Lacertilia）的同义词。但因为蜥蜴本身是个并系群，在1984年，嘉克斯·高斯特（Jacques Gauthier）正式命名蜥类（Sauria），并创建系统发生学定义。

The clade Sauria was traditionally a suborder for lizards which originally (before 1800) comprised crocodilians too. It has been redefined as the group containing the most recent common ancestor of archosaurs and lepidosaurs and all its descendants; as such it was commonly thought that Sauria is a crowned-base grouping of diapsids. However, recent genomic studies and comprehensive studies in the fossil record suggest that turtles are closely related to archosaurs, not to parareptiles as previously thought. As such Sauria can be seen as a crowned-group of all modern reptiles (including birds) within the larger total group Sauropsida, which also contains various stem-reptile groups.