The Greenish Warbler (Phylloscopus trochiloides) are widespread leaf warblers throughout their breeding range in northeastern Europe and temperate to subtropical continental Asia. This warbler is strongly migratory and winters in India. It is not uncommon as a spring or early autumn vagrant in Western Europe and is annually seen in Great Britain.

This is a typical leaf warbler in appearance, grayish-green above and off-white below. The single wing bar found in the southern and western populations distinguishes them from most similar species (except Arctic Warbler P. borealis). It is slightly smaller than that species and has a thinner bill, without a dark tip to the lower mandible.

Its song is a high jerky trill, in some populations containing a sequence of down- and more rarely up slurred notes.

It breeds in lowland deciduous or mixed forest; non-breeding birds in the warmer parts of its range may move to montane habitat in summer. Individuals from southeast of the Himalayas are for example quite often seen in Bhutan during the hot months, typically in humid Bhutan Fir (Abies densa) forest up to about 3,800 meters ASL or more, but they do not breed there and return again to the adjacent subtropical lowlands in winter.