Holly (Ilex) is a genus of about 400 species of flowering shrubs and trees that grows wild and is cultivated in Asia, Europe, northern Africa, and Americas. It can be either deciduous or evergreen depending on the species.

The flowers of the Holly open up in May or June, and develop on the female plants into pea-sized, red berries which remain through the winter. These berries are very bitter so are rarely eaten by birds until late winter when frost makes them softer and edible. The Holly berries are poisonous to people, and eating a number of them will cause stomachache, vomiting and diarrhea.

The hard white wood of the plant is used for cabinetmaking.

The leaves of this plant are reputed to have astringent, diuretic, expectorant and febrifuge properties.

In the Druidic culture Holly was considered as a holy tree. Its name (Old English "holegn") is directly related to "holy".

The Holly has long been used as traditional Christmas decoration.