Eurema simulatrix, the changeable grass yellow, is a butterfly in the family Pieridae. It is found from Burma to Sundaland and the Philippines. The habitat consists of secondary or disturbed habitats including forest clearings, roadsides and riverbanks, parks and gardens. The length of the forewings is 21–26 mm (0.83–1.02 in) for males and 19–25 mm (0.75–0.98 in) for females. Adults have two cell spots on the underside of the forewings and a large, almost cleft, reddish-brown apical spot on the forewing. The following subspecies are recognised: Eurema irena is sometimes treated as a subspecies of Eurema simulatrix.