Thomas Littleton Powys, 4th Baron Lilford was a British aristocrat and ornithologist. He was one of the eight founders of the British Ornithologists' Union in 1858, and its president from 1867 until his death. He was also the first President of the Northamptonshire Natural History Society. He travelled widely, especially around the Mediterranean and his extensive collection of birds was maintained in the grounds of Lilford Hall. Until 1891, his aviaries featured birds from around the globe, including rheas, kiwis, Pink-headed ducks and a pair of free-flying Bearded vultures. He was responsible for the introduction of the Little owl into England in the 1880s. He wrote about birds including Notes on the Birds of Northamptonshire and Neighbourhood (1895) and Coloured Figures of the Birds of the British Islands, which was completed by Osbert Salvin after his death. A species of European lizard, Podarcis lilfordi, is named in his honour