The Ahool is an avian cryptid believed to reside in the mountainous rain forests of Java, the fourth largest island of Indonesia. Said to stand between 3 and 4 feet tall, the Ahool is reported to have a 12 foot wing span, with leathery wings and sharp claws on each forearm. The creature is described as having course grey fur and resembling a large bat or flying primate. Said to feed on large fish, the Ahool gets its name from the distinctive “ah-hooool” call it is said to make while hunting.

The first known sighting of the Ahool is believed to have occurred in 1925 when Dr. Earnest Bartels, observed what he believed to be a large bat flying overhead while exploring a waterfall in the Salek Mountains. In 1927, Bartels again believed he encountered the creature, this time identifying it based wholly on its distinctive call. Later, Bartels’ account was shared with Ivan T. Sanderson, a British biologist who is considered by many to be the father of cryptozoology. Intrigued, Sanderson researched the matter further, eventually concluding the creature was an unclassified species of bat.

While many cryptozoologists concur with Sanderson’s findings, there are other theories. Among these, that the Ahool is a flying primate, or even a surviving pterosaur, a flying reptile believed to have gone extinct 65 million years ago. For those who subscribe to the bat theory, parallels are drawn between the Ahool and other large, flying cryptids with similar, bat-like descriptions. These include the Orang Bati from the nearby island of Seram, New Guinea’s Reopen and the African Kongamato, all thought to possibly belong to the Peteropus genus of megabats which includes Pteropus vampyrus, more commonly known as the Large Flying Fox and the world's largest bat.