Heteronympha merope, the common brown, is a species of butterfly of the family Nymphalidae, endemic to the southern half of Australia. The wingspan is about 60 mm for males and 70 mm for females. The larvae feed on Poaceae species, including Brachypodium distachyon, Cynodon dactylon, Ehrharta erecta, Poa poiformis, Microlaena stipoides, Poa tenera and Themeda triandra. The common brown butterfly is emerging ten days earlier than it did 65 years ago due to the effects of climate change.