Camellia, the Camellias, is a genus of flowering plants in the family Theaceae. They are found in eastern and southern Asia, from the Himalaya east to Korea and Indonesia. There are 100–250 described species, with some controversy over the exact number. The genus was named by Linnaeus after the Jesuit botanist Georg Joseph Kamel from Brno, who worked in the Philippines, though he never described a camellia. This genus is famous throughout East Asia; camellias are known as cháhua in Chinese, "flowering tea", an apt designation, as tsubaki in Japanese, as dongbaek-kkot in Korean and as hoa trà or hoa chè in Vietnamese.

The most famous member – though often not recognized as a camellia – is certainly the tea plant (C. sinensis). Among the ornamental species, the Japanese Camellia (C. japonica) (which despite its name is also found in Korea and Eastern China) and C. sasanqua are perhaps the most widely known, though most camellias grown for their flowers are cultivars or hybrids.

Camellias are evergreen and small trees up to 20 meters tall. Their leaves are alternately arranged, simple, thick, serrated, and usually glossy.Their flowers are usually large and conspicuous, one to 12 cm in diameter, with five to nine petals in naturally occurring species of camellias. The colors of the flowers vary from white through pink colors to red; truly yellow flowers are found only in South China and North Vietnam. Camellia flowers throughout the genus are characterized by a dense bouquet of conspicuous yellow stamens, often contrasting with the petal colors. The so-called "fruit" of camellia plants is a dry capsule, sometimes subdivided in up to five compartments, each compartment containing up to eight seeds.

The various species of camellia plants are generally well-adapted to acidic soils rich in humus, and most species do not grow well on chalky soil or other calcium-rich soils. Most species of camellias also require a large amount of water, either from natural rainfall or from irrigation, and the plants will not tolerate droughts. However, some of the more unusual camellias – typically species from karst soils in Vietnam can grow without too much water.

Camellia plants usually have a rapid growth rate. Typically they will grow about 30 cm per year until mature – though this does vary depending on their variety and geographical location. Camellia plants are used as food plants by the larvae of a number of Lepidoptera species; see List of Lepidoptera that feed on Camellia. Leaves of the Japanese Camellia (C. japonica) are suceptable to the fungal parasite Mycelia sterile.