Coordinates: 21°08′07″S 55°28′16″E / 21.1353°S 55.4711°E / -21.1353; 55.4711

Cilaos is a town and commune on the French island of Réunion in the Indian Ocean. It is located centrally on the island, in a caldera of altitude 1214 m. The caldera (usually known as the 'Cirque') is also named for the community.

The name Cilaos comes from the Malagasy word, Tsilaosa (modern form : tsy ilaozana), which means the place one never leaves.

According to some historians, the word Cilaos finds its origins in the name of a Malagasian slave named Tsilaos who took refuge in this cirque. At the time, slaves were called "brown", whereas runaway slaves were called "black-brown".

The first inhabitants of the cirque of Cilaos were thus "black-browns" who believed themselves to be at the top of the world and completely safe. However, these first runaways were recaptured very quickly, tracked and hunted by well-organized and well-armed slaveholders. In these runaways' attempts to escape recapture, several were killed. It seems likely that these first runaways created the goat paths that climb most of the mountains on Réunion.