The penal colony of Cayenne (French: Bagne de Cayenne), commonly known as Devil's Island (le du Diable), was a French penal colony that operated for more than 100 years, from 1852 to 1953, in the Salvation Islands of French Guiana.

Opened in 1852, the Devil's Island system received convicts from the Prison of St-Laurent-du-Maroni, who had been deported from all parts of the Second French Empire. It was notorious both for the staff's harsh treatment of detainees and the tropical climate and diseases that contributed to high mortality. The prison system had a death rate of 75% at its worst, and was finally closed down in 1953.Devil's Island was also notorious for being used for the exile of French political prisoners, with the most famous being Captain Alfred Dreyfus, accused of spying for Germany. The Dreyfus affair was a scandal extending for several years in late 19th-early 20th century France, exposing antisemitism and corruption in the French military.

A penal colony or exile colony is a settlement used to exile prisoners and separate them from the general population by placing them in a remote location, often an island or distant colonial territory. Although the term can be used to refer to a correctional facility located in a remote location it is more commonly used to refer to communities of prisoners overseen by wardens or governors having absolute authority.

Historically penal colonies have often been used for penal labour in an economically underdeveloped part of a state's (usually colonial) territories, and on a far larger scale than a prison farm.