Cotoneaster is a genus of woody plants in the rose family, Rosaceae, native to the Palaearctic region (temperate Asia, Europe, north Africa), with a strong concentration of diversity in the genus in the mountains of southwestern China and the Himalayas. They are related to hawthorns (Crataegus), firethorns (Pyracantha), photinias (Photinia) and rowans (Sorbus). Depending on the species definition used, there are between 70 to 300 different species of cotoneaster, with many apomictic microspecies treated as species by some authors, but only as varieties by others.

The majority of species are shrubs from 0.5–5 metres (1.6–16 ft) tall, varying from ground-hugging prostrate plants to erect shrubs; a few, notably C. frigidus, are small trees up to 15 metres (49 ft) tall and 75 centimetres (30 in) trunk diameter. The prostrate species are mostly alpine plants growing at high altitude (e.g. C. integrifolius, which grows at 3,000–4,000 metres (9,800–13,000 ft) in theHimalayas), while the larger species occur in scrub and woodland gaps at lower altitudes.

The shoots are dimorphic, with long shoots (10–40 centimetres/3.9–16 inches long) producing structural branch growth, and short shoots (0.5–5 centimetres/0.20–2.0 inches long) bearing the flowers; this pattern often developing a ‘herringbone’ form of branching. The leaves are arranged alternately, 0.5–15 centimetres (0.20–5.9 in) long, ovate to lanceolate, entire; both evergreen and deciduousspecies occur. The flowers are produced in late spring through early summer, solitary or in corymbs of up to 100 together. The flower is either fully open or has its five petals half open 5–10 millimetres (0.20–0.39 in) diameter. They may be any shade from white through creamy white to light pink to dark pink to almost red, 10-20 stamens and up to five styles. The fruit is a small pome 5–12 millimetres (0.20–0.47 in) diameter, pink or bright red, orange or even maroon or black when mature, containing one to three (rarely up to five) seeds. Fruit on some species stays on until the following year.

Cotoneaster species are used as larval food plants by some Lepidoptera species including Grey Dagger, Mottled Umber, Short-cloaked Moth, Winter Moth and Hawthorn Moth (Scythropia crataegella). The flowers attract bees and butterflies and the fruits are eaten by birds.

Although relatively few species are native there, in the UK and Ireland Cotoneaster species are used, along with the related genus Pyracantha, as a valuable source of nectar when often the bees have little other forage in the June Gap. The red berries are also highly attractive to blackbirds and other thrushes.

Cotoneasters are very popular garden shrubs, grown for their attractive habit and decorative fruit. Many of the garden shrubs are cultivars, some of hybrid origin; of these, some are of known parentage, such as the very popular Cotoneaster × watereri Exell (Waterer’s Cotoneaster; C. frigidus × C. salicifolius), while others not. Many species have escaped from cultivation and become invasive weedswhere climatic conditions are suitable for them, such as the many Chinese species naturalised in northwestern Europe. C. glaucophyllus have become invasive weeds in Australia and California.C. simonsii is listed on the New Zealand National Pest Plant Accord preventing its sale and distribution because of its invasiveness.