The Flandrian interglacial or stage is the name given by geologists and archaeologists in the British Isles to the first, and so far only, stage of the Holocene, covering the period from around 10,000 years ago when the last ice age ended to the present day. As such, it is in practice identical in span to the Holocene.

It follows the Devensian glaciation, the last stage of the Pleistocene and is traditionally seen as the latest warm interglacial in a series that has been occurring throughout the Quaternary system.