High electron mobility transistors (HEMTs) and methods of manufacturing the same. A HEMT may include a channel layer and a channel supply layer, and the channel supply layer may be a multilayer structure. The channel supply layer may include an etch stop layer and an upper layer on the etch stop layer. A recess region may be in the upper layer. The recess region may be a region recessed to an interface between the upper layer and the etch stop layer. A gate electrode may be on the recess region.