Eucalyptus camaldulensis, commonly known as river red gum, is a flowering plant in the family Myrtaceae, and is endemic to Australia. It is a tree with smooth white or cream-coloured bark, lance-shaped or curved adult leaves, flower buds in groups of seven or nine, white flowers and hemispherical fruit with the valves extending beyond the rim. A familiar and iconic tree, it is seen along many watercourses across inland Australia, providing shade in the extreme temperatures of central Australia and elsewhere.

Eucalyptus camaldulensis is a tree that typically grows to a height of 20 metres (66 ft) but sometimes to 45 metres (148 ft) and often does not develop a lignotuber. The bark is smooth white or cream-coloured with patches of yellow, pink or brown. There are often loose, rough slabs of bark near the base. The juvenile leaves are lance-shaped, 80–180 mm (3.1–7.1 in) long and 13–25 mm (0.51–0.98 in) wide. Adult leaves are lance-shaped to curved, the same dull green or greyish green colour on both sides, 50–300 mm (2.0–11.8 in) long and 7–32 mm (0.28–1.26 in) wide on a petiole 8–33 mm (0.31–1.30 in) long. The flower buds are arranged in groups of seven, nine or sometimes eleven, in leaf axils on a peduncle 5–28 mm (0.20–1.10 in) long, the individual flowers on pedicels 2–10 mm (0.079–0.394 in) long. Mature buds are oval to more or less spherical, green to creamy yellow, 6–9 mm (0.24–0.35 in) long and 4–6 mm (0.16–0.24 in) wide with a prominently beaked operculum 3–7 mm (0.12–0.28 in) long. Flowering mainly occurs in summer and the flowers are white. The fruit is a woody, hemispherical capsule 2–5 mm (0.079–0.197 in) long and 4–10 mm (0.16–0.39 in) wide on a pedicel 3–12 mm (0.12–0.47 in) long with the valves raised above the rim. The plant's flowers bloom for a long time throughout the year.

The limbs of river red gums, sometimes whole trees, often fall without warning so that camping or picnicking near them is dangerous, especially if a tree has dead limbs or the tree is under stress.

Eucalyptus camaldulensis was first formally described in 1832 by Friedrich Dehnhardt who published the description in Catalogus Plantarum Horti Camaldulensis.

Seven subspecies of E. camaldulensis have been described and accepted by the Australian Plant Census. The most variable character is the shape and size of the operculum, followed by the arrangement of the stamens in the mature buds and the density of veins visible in the leaves. The subspecies are:

The specific epithet (camaldulensis) is a reference to a private estate garden (L'Hortus Camaldulensis di Napoli) near the Camaldoli monastery in Naples, where Frederick Dehnhardt was the chief gardener. The type specimen was grown in the gardens from seed presumably collected in 1817 near Condobolin by Allan Cunningham, and was grown there for about one hundred years before being removed in the 1920s. Herbarium specimen of the holotype is deposited in the herbarium of Natural History Museum of Vienna.

Although Dehnhardt was the first to formally describe E. camaldulensis, his book was largely unknown to the botanical community. In 1847 Diederich von Schlechtendal gave the species the name Eucalyptus rostrata but the name was illegitimate (a nomen illegitimum) because it had already been applied by Cavanilles to a different species (now known as Eucalyptus robusta). In the 1850s, Ferdinand von Mueller labelled some specimens of river red gum as Eucalyptus longirostris and in 1856 Friedrich Miquel published a description of von Mueller's specimens, formalising the name E. longirostris. Finally in 1934, William Blakely recognised Dehnhardt's priority and the name E. camaldulensis for river red gum was accepted.

Northern Territory Aboriginal names for this species are: