The Philippine eagle is considered the largest of the extant eagles in the world in terms of length and wing surface area, with only Steller's sea eagle and the Harpy eagle being larger in terms of weight and bulk. It has been declared the national bird of the Philippines. It is also depicted in the Philippine one thousand-peso note.The species had been classified by the IUCN Red List as critically endangered with a declining population and is one of the most endangered raptors in the world. The most significant threat to the species is loss of habitat, a result of high levels of deforestation throughout most of its range. Since 2019, more than 20 eagles have been rescued mostly due to injuries from gunshot wounds.
Killing a Philippine eagle is a criminal offence, punishable by law with up to 12 years' imprisonment and heavy fines. The Philippine eagle has numerous native names in the Philippine languages. These include bánoy and ágila (a Spanish loanword) in Tagalog; manaul or manaol in the Visayan languages; manaol or garuda in Maranao and Maguindanao; tipule in Subanen; and mam-boogook or malamboogook in the Manobo languages, Klata, Tagabawa, Mandaya, and Kalagan. Some of these names are also used for other large eagles in general, such as the white-breasted sea eagle (also called manaul in Visayan). In modern Filipino, it is usually referred to as háribon (a portmanteau of "háring ibon", literally "bird king").
The first European to study the species was the English explorer and naturalist John Whitehead in 1896, who observed the bird and whose servant, Juan, collected the first specimen a few weeks later. The skin of the bird was sent to William Robert Ogilvie-Grant in London in 1896, who initially showed it off in a local restaurant and described the species a few weeks later.
Upon its scientific discovery, the Philippine eagle was first called the monkey-eating eagle because of reports from natives of Bonga, Samar, where the species was first discovered, that it preyed exclusively on monkeys. These reports gave its generic name, from the Greek pithecus (πίθηκος, "ape" or "monkey") and phagus (-φάγος, "eater of"). The species name commemorates Jeffery Whitehead, the father of John Whitehead. Later studies revealed, however, that the alleged monkey-eating eagle also ate other animals, such as colugos, large snakes, monitor lizards, and even large birds such as Hornbills. This, coupled with the fact that the same name applied to the African Crowned eagle and the Central and South American Harpy eagle, it was renamed "Philippine eagle" in a 1978 proclamation by then-President Ferdinand Marcos. In 1995, it was declared a national emblem under President Fidel V. Ramos. This species has no recognized subspecies.