Gerald Percy Vivian Aylmer, known as either Percy or Vivian, was a British big game hunter and explorer of Africa. He was born at his family home of Walworth Castle, County Durham, and attended Eton and Trinity College, Cambridge. Aylmer and his brother, Edmund, inherited the castle when their parents were killed in the Abergele rail disaster. Aylmer was 12 years old at the time.

Aylmer was a participant in an expedition to north Somaliland in 1884-1885, during which much natural history material was collected before the party was ordered to return to Britain, following the siege of Khartoum. The other travellers were brothers F.L. and W.D. James and expedition leader Ethelbert Lort-Philips. Most of the plants from the expedition were actually collected by the wife of Lort-Phillips and Miss Edith Cole, and come from the area south of Berbera, extending to the Golis range of mountains.

Aylmer was appointed Justice of the Peace and High Sheriff of Durham in 1887, and served in the Boer War in 1899-1900. He died in Newcastle-upon-Tyne in 1931.

Gerald Aylmer should not be confused with Guy Aylmer, Conservator of Forests in Sudan and Sierra Leone, who also made natural history collections and appears on labels as G. Aylmer.

Sources:
1937, Nature, 139: 142
J.G. Baker, 1895, "Diagnoses Africanae VII", Kew Bulletin of Miscellaneous Information, 1895(105): 211.