A beautiful Russian documentairy video (translated into English) about the Amur Leopard, certainly the leopard species most clearly endagered by the very small number of animals left in the wild (in 1972, it was evaluated that their number was below 40 animals).
YouTube link
more recently, thanks to scientific studies organized by ALTA – Amur Leopard Conservation, it has been shown that their number may be growing very slowly again.
Panthera pardus orientalis Critically Endangered according to the IUCN.