Bilberry is a name given to several species of low-growing shrubs in the genus Vaccinium (family Ericaceae) that bear tasty fruits.

The species most often referred to is Vaccinium myrtillus L., also known as blaeberry, whortleberry, whinberry, myrtle blueberry, and probably other names regionally.

The word bilberry is also sometimes used in the common names of other species of the genus, including Vaccinium uliginosum L. (bog bilberry, bog blueberry, bog whortleberry, bog huckleberry, northern bilberry), Vaccinium caespitosum Michx. (dwarf bilberry), Vaccinium deliciosum Piper (Cascade bilberry), Vaccinium membranaceum (mountain bilberry, black mountain huckleberry, black huckleberry, twin-leaved huckleberry), and Vaccinium ovalifolium (oval-leafed blueberry, oval-leaved bilberry, mountain blueberry, high-bush blueberry).

Bilberries are found in damp, acidic soils throughout the temperate and subarctic regions of world. They are closely related to North American wild and cultivated blueberries and huckleberries in the genus Vaccinium. The easiest way to distinguish the bilberry is that it produces single or pairs of berries on the bush instead of clusters like the blueberry. Bilberry is used as a food plant by the larvae of some Lepidoptera species including Common Marbled Carpet and Common Pug.

Bilberries are rarely cultivated but fruits are sometimes collected from wild plants growing on public lands, notably in Scandinavia and Poland. Vaccinium myrtillus fruit is called blåbär in Swedish and mustikka in Finnish; Vaccinium uliginosum fruit is odon in Swedish and juolukka in Finnish. The fruits are eaten fresh, or are usually made into jams, juices or pies. They have therapeutic uses in herbal medicine.