The Bonin white-eye (Apalopteron familiare) is a small species of songbird endemic to the Bonin Islands (Ogasawara Islands) of Japan. It is the only species in the monotypic genus Apalopteron. The taxonomic affinities of the Bonin white-eye were a long-standing mystery and it was formerly placed with the bulbuls, babblers and more recently with the honeyeaters, during which it was known as the Bonin honeyeater. Since 1995 it is known to be a white-eye in the family Zosteropidae, that is closely related to the golden white-eye of the Marianas Islands.

The Bonin white-eye has predominately yellow and green plumage and a conspicuous black triangular patch around the eye – the eye is also surrounded by a broken white ring. It was once found on all the major islands of the Bonin Islands but is now restricted to the islands of Hahajima. On that island group it is found in almost all the habitat types, native and human-modified, although it mostly breeds in native forest. Fruit is an important part of the diet, especially mulberries, as well as insects, but flowers, seeds, spiders and reptiles are taken as well. It feeds both in trees and on the ground, as it is more terrestrial than other white-eyes. Pairs of Bonin white-eyes form long-term pair bonds and remain together throughout the year. They nest in a cup-shaped nest into which usually two eggs are laid. Both parents are responsible for incubation and raising the chicks.

The arrival of humans in the Bonin Islands resulted in the extinction of many of the native birds of the islands. The Bonin white-eye was affected by the changes that caused those extinctions, and has lost one subspecies and is no longer found on many groups of the Bonin Islands. The species is an important part of the ecology of the Bonin Islands, an important seed disperser for the native plants. It has proven to be somewhat resilient to competition from introduced warbling white-eyes, predation by introduced rats and cats, and habitat loss. The Bonin white-eye is evaluated as being "near threatened" by the IUCN Red List of Threatened Species.

The Bonin white-eye was described by Heinrich von Kittlitz in 1830 based on specimens collected on Chichijima in the Bonin Islands. Kittlitz placed the species in the bulbul (family Pycnonotidae) genus Ixos. He gave the species the specific name familiare from the Latin for familiar or friendly, as the species was the first bird that visitors would encounter, much like the house sparrow in Europe. In 1854 Charles Lucien Bonaparte moved it to its own genus, Apalopteron. The name is derived from the Ancient Greek hapalos for delicate and ptilon for feather. Bonaparte also placed it with the Old World babblers, then a subgrouping (Timaliini) of an enlarged Old World warbler family (Sylviidae). Richard Bowdler Sharpe moved it back to the bulbul family in 1882, and placed it in the genus Pycnonotus. It was moved back to the babblers again by Jean Théodore Delacour in 1946, before Herbert Girton Deignan placed it with the Australasian honeyeaters (family Meliphagidae) in 1958, on the basis of tongue structure, bill shape, nest structure and a number of other morphological features.

The species remained with the honeyeaters for many decades, although some authors questioned the placement, especially as it was the only honeyeater in the North Pacific and there were no members of that family in the Philippines, the island group between that family's natural range and the Bonin Islands. Finn Salomonsen, writing in 1967, thought that the golden white-eye (Cleptornis marchei) of the Marianas Islands might be a close relative, and the species was then known as the golden honeyeater. Hiroyuki Morioka and Takaharu Sakane also attributed the species to the honeyeaters, but cautioned that this was a provisional placement as the structure of the tongue was not very different from that of babblers. They also noted that it was very similar in diet and habitat preferences to the warbling white-eye, which had been introduced and was coexisting with the Bonin white-eye.

The discovery that the golden white-eye was indeed a white-eye and not a honeyeater, based on behavioural observations by H. Douglas Pratt and the genetic research of Charles Sibley and Jon E. Ahlquist, was the impetus for the resolution of the Bonin white-eye's family placement. Sibley came to suspect that this meant that the Bonin white-eye had been similarly misassigned to the honeyeaters. Hiroyoshi Higuchi independently had reached the same conclusion, and so Higuchi and Keisuke Ueda obtained specimens for Sibley, who enlisted Mark S. Springer to analyse them using RNA sequencing. In 1995 they were able to show that it was indeed a white-eye (family Zosteropidae), and closely related to the golden white-eye and the white-eyes of the genus Rukia of Micronesia. The molecular evidence was supported by behavioural similarities to the white-eyes, such as the highly social allopreening and maintaining close contact when roosting.

There are two subspecies of Bonin white-eye, the extinct nominate, formerly found in Mukojima and Chichijima, and the southern subspecies, A. f. hahasima, of Hahajima.

The Bonin white-eye is 12 to 14 cm (4.7–5.5 in) long and weighs around 15 g (0.53 oz). The nominate race has a yellow head with a conspicuous triangular black eye-patch which is linked by the thin black line to a black forehead. The white eye-ring is broken by a thin black line through the eye. The lores are yellow, as are the throat and upper breast. The back and wings are olive-green tinged with grey, and the primaries are tinged with brown. The tail is olive-brown, and the underparts are pale yellow, with a grey wash on the flanks. The iris of the eye is brown, and the bill and legs are dark grey. The sexes are alike, and juveniles look very similar to the adults. The race hahasima is very similar to the nominate race, but the upperparts are tinged in yellowish-green tinge. It also has a slightly larger bill and tarsus.