The Small Heath (Coenonympha pamphilus) looks similar to the Meadow Brown (Maniola jurtina) and the Gatekeeper (Pyronia tithonus), but is distinguished by its much smaller size and the hairy backs of the wings.

1st photo: Hortobágy-Halastó, Hortobágy National Park, Hungary, 2 May 2019
2nd & 3rd photo: Polgár Fishponds, Hortobágy National Park, Hungary, 30 April 2019