Angraecum sesquipedale , also known as Darwin's orchid, Christmas orchid, Star of Bethlehem orchid, and King of the angraecums, is an epiphytic orchid in the genus Angraecum endemic to Madagascar. The orchid was first discovered by the French botanist Louis-Marie Aubert du Petit-Thouars in 1798, but was not described until 1822. It is noteworthy for its long spur and its association with the naturalist Charles Darwin, who surmised that the flower was pollinated by a then undiscovered moth with a proboscis whose length was unprecedented at the time. Darwin's prediction went unverified for 21 years after his death, until just such a moth was discovered and his conjecture vindicated. The story of its postulated pollinator has come to be seen as one of the celebrated predictions of the theory of evolution.

Angraecum sesquipedale is a monopodial orchid and can grow to a height of 1 m (3.3 ft). The leaves are dark green with a bit of a grayish tone and leathery with a bilobed tip. They are usually around 20–40 centimeters (7.9–15.7 in) long and 6–8 cm (2.4–3.1 in) wide. The roots are dark gray, thick, and emerge from the orchid's stem. There tend to be few roots and they attach to the bark of the trees quite strongly. Each of the succulent roots can extend along the trunk of the tree for several meters.

Its famously long nectar spurs which extend from the back of the flower grow on average to a length of 33 cm, but can grow as long as 43 cm, or as short as 27 cm.