The Coffin Stone, also known as the Coffin and the Table Stone, is a large sarsen stone at the foot of Blue Bell Hill near Aylesford in the south-eastern English county of Kent. Now lying horizontally, the stone probably once stood upright nearby. Various archaeologists have argued that the stone was part of a now-destroyed chambered long barrow constructed in the fourth millennium BCE, during Britain's Early Neolithic period.

If a chambered long barrow did indeed previously exist on the site, it would have been built by pastoralist communities shortly after the introduction of agriculture to Britain from continental Europe. Long-barrow building was an architectural tradition widespread across Neolithic Europe. It consisted of various localized regional variants; one of these was in the vicinity of the River Medway, examples of which are now known as the Medway Megaliths. The Coffin Stone lies on the eastern side of the river, not far from the chambered long barrows of Little Kit's Coty House, Kit's Coty House, and the (now destroyed) Smythe's Megalith. Three other examples, the Coldrum Long Barrow, Addington Long Barrow, and Chestnuts Long Barrow, remain on the western side of the river.

The Coffin Stone is a rectangular slab lying flat that measures 4.42 metres (14 ft 6 in) in length, 2.59 metres (8 ft 6 in) in breadth, and about 0.61 metres (2 ft) in width. Two smaller stones lie nearby and another large slab is now located atop it. In the 1830s it was reported that local farmers found human bones near the stone. An archaeological excavation of the site led by Paul Garwood took place in 2008–09; it found that the megalith was placed in its present location only in the 15th or 16th centuries. The archaeologists found no evidence of a chambered long barrow at the location, and suggested that the Coffin Stone might once have stood upright in the vicinity.

The Coffin Stone is in Great Tottington Farm, which is now used as a vineyard. As of 2005, the site was not signposted, but could be reached via a stile along the Pilgrims' Way. The Coffin Stone is situated about 400 metres (1,300 ft) north-west of Little Kit's Coty House. It is also a short distance north of the Tottington springhead.

The Early Neolithic was a revolutionary period of British history. Between 4500 and 3800 BCE, it saw a widespread change in lifestyle as the communities living in the British Isles adopted agriculture as their primary form of subsistence, abandoning the hunter-gatherer lifestyle that had characterised the preceding Mesolithic period. This came about through contact with continental societies; it is unclear to what extent this can be attributed to an influx of migrants or to indigenous Mesolithic Britons adopting agricultural technologies from continental Europe. The region of modern Kent was a key area for the arrival of continental settlers and visitors, because of its position on the estuary of the River Thames and its proximity to the continent.

Britain was largely forested in this period; widespread forest clearance did not occur in Kent until the Late Bronze Age (c.1000 to 700 BCE). Environmental data from the vicinity of the White Horse Stone, a putatively prehistoric monolith near the River Medway, supports the idea that the area was still largely forested in the Early Neolithic, covered by a woodland of oak, ash, hazel/alder and Maloideae (apples and their allies). Throughout most of Britain, there is little evidence of cereal grain farming or permanent dwellings from this period, leading archaeologists to believe that the Early Neolithic economy on the island was largely pastoral, relying on herding cattle, with people living a nomadic or semi-nomadic life.

Across Western Europe, the Early Neolithic marked the first period in which humans built monumental structures. These included chambered long barrows, rectangular or oval earthen tumuli that had a chamber built into one end. Some of these chambers were constructed out of timber, and others were built using large stones, now known as "megaliths". Long barrows often served as tombs, housing the physical remains of the dead within their chamber. Individuals were rarely buried alone in the Early Neolithic, instead being interred in collective burials with other members of their community. Chambered tombs were built all along the Western European seaboard during the Early Neolithic, from southeastern Spain to southern Sweden, taking in most of the British Isles; the architectural tradition was introduced to Britain from continental Europe in the first half of the fourth millennium BCE. There are stone buildings—like Göbekli Tepe in modern Turkey—that predate them, but the chambered long barrows constitute humanity's first widespread tradition of construction using stone.

Although now all in a ruinous state and not retaining their original appearance, at the time of construction the Medway Megaliths would have been some of the largest and most visually imposing Early Neolithic funerary monuments in Britain. Grouped along the River Medway as it cuts through the North Downs, they constitute the most southeasterly group of megalithic monuments in the British Isles, and the only megalithic group in eastern England. The archaeologists Brian Philp and Mike Dutto deemed the Medway Megaliths to be "some of the most interesting and well known" archaeological sites in Kent, while the archaeologist Paul Ashbee described them as "the most grandiose and impressive structures of their kind in southern England".