The Civil Guard said the private collection, estimated to be worth nearly 29 million euros ($32 million), was discovered in a shed in Betera, near Valencia in eastern Spain.
Among the 1,090 animals seized, 405 are classified as protected, endangered or extinct, including the scimitar-horned oryx once found in parts of Africa.
A stuffed Bengal tiger, considered near extinction, was also found, along with cheetahs, lynxes, polar bears, white rhinos and 198 elephant tusks.
The Civil Guard said on Sunday it was the country’s “largest haul of nationally-protected taxidermied animals and one of the largest in Europe”.
The owner of the collection is under investigation for smuggling and several environmental crimes.