The green-headed hillstar, Oreotrochilus estella stolzmanni, is a species of hummingbird found in the Andes in far southern Ecuador and northern and central Peru in alpine grassland and scrub at altitudes of 3,600 to 4,200 metres (11,800 to 13,800 ft). It is usually considered a subspecies of the Andean hillstar, Oreotrochilus estella, but the male of that species has duller upperparts and a brown (not black) line to the central underparts. The binomial name commemorates Polish ornithologist Jan Sztolcman (Jean Stanislaus Stolzmann).