Aberthaw (Welsh: Aberddawan) is an area containing the villages of East Aberthaw and West Aberthaw, on the coast of South Wales about 5 miles (8 km) west of Barry. It is the location of Aberthaw Cement Works, Aberthaw Lime Works, and Aberthaw Power Station, a decommissioned coal power station that was linked to the South Wales Valleys via the Vale of Glamorgan Railway. The area is historically within the parish of Penmark in the Vale of Glamorgan. The two villages of West and East Aberthaw are separated by the River Thaw. The village of East Aberthaw, near Rhoose, has a 13th-century pub. The village Baptist Chapel and Mission Room no longer exist as such and have been converted for other uses.

Aberthaw is nearly opposite Minehead in Somerset, England. The village of East Aberthaw is situated approximately 0.25 miles (0.40 km) inland from the sea. The River Thaw, which meets the sea at Aberthaw, is fairly small and is affected by high tides at times, and with the coming of the first coal-fired power station at Aberthaw circa 1958, was diverted to form a straight channel about 959 yards long from the fixed coastline and this section is therefore within the Power Generation Board's property. Its former tributary now forms an enclosed pond area near the old lime works and is rich in wildlife. From Dunraven to Aberthaw, the coastal cliffs feature blue and brown argillaceous limestones, shales, and marls. As far as East Aberthaw, the cliffs are under 100 feet (30 m), and in some places not more than 50 feet (15 m). For a short distance east of Pleasant Harbour in East Aberthaw, there are wooded cliffs about 300 yards from the high-water mark of ordinary tides. West of the port of Aberthaw there is an expanse of alluvial ground protected by embankments. This is bordered by hillocks of blown sand, and these rise about 20 feet (6.1 m) above the shingle beach. Bordering the blown sand, there is a ridge of thick shingle, and beyond this, between tide-marks, is an expanse of shingle on mud. There are no cliffs to the west of Aberthaw until Summerhouse Point. Font-y-Gary Cave is near Aberthaw.

The beach in front of the power station, The Leys, is near Gileston and West Aberthaw; it is well known for its sea fishing. The East Aberthaw Coast Conservation Area covers the whole of the East Aberthaw village and contains a lagoon on The Leys. Breaksea Point, at the edge of Limpert Bay at Aberthaw, is sometimes regarded as the southernmost point of Wales, although this is contested with Rhoose Point; nevertheless, the Vale of Glamorgan Council has decreed that Rhoose Point is the most southerly and has placed a notice board to that effect on the coastal footpath at Rhoose Point.

Aberthaw derives its name from the Welsh word 'aber', meaning estuary or river mouth, of the river Thaw. The existence of a safe, natural harbour provided an early impetus for the area's development and trade. There were settlements in the second and third centuries, substantiated by Roman pottery, shells and tiles that were discovered when a new pipeline was laid through East Aberthaw in the 1950s. Excavations in Well Road revealed the foundations of walls which may have belonged to the Roman settlement, while further discoveries of coins, jewellery, tiles and Samian ware pottery suggested that the nearby bay served as a landing point or port during the Roman invasion. The Shrunken Village at West Aberthaw, considered an Ancient Monument in Glamorgan, consisted of a shrunken hamlet within a narrow strip of St. Athan parish which extended to the Bristol Channel.

A small village centred around the intersection of two roads had developed by the medieval period. To the east, what is now Port Road led towards Fonmon and Penmark, whilst to the west, the present Well Road (previously known as Marshe Way) led towards the marshland and a ford across the estuary. The road leading north- south connected the coast with the settlements inland, and as Aberthaw trade flourished, the roads were used for moving imported goods to the markets at St. Athan and Cowbridge.

Of the buildings grouped around the crossroads, the original fabric of Lower Farm House and the once- thatched Rose Cottage and Marsh Cottages can all be dated to the medieval era. The Blue Anchor Inn is likewise of medieval origin, and appears to have been erected in 1380. The village, which came within the parish of Penmark, is also known to have included a small chapel which was possibly located towards the south of the settlement, as suggested by the marking of 'Chapplefeld' on the Evans Mouse map of 1622. This was to serve as a place of worship until being converted to a house at the turn of the 17th century.

In the 16th century, the Aberthaw port, situated to the southeast of the village proper, had emerged as a small but thriving harbour. The ships took wool and foodstuffs from Wales and returned with wine, salt, dried fruit and leather from the towns of northern France. Aberthaw port's importance was furthered by the loss of Porthkerry harbour to a 1584 storm, rendering Aberthaw the principal calling-point within South Wales between Cardiff and Swansea.

By the first half of the 17th century, boats were departing for not only England and France, but also Spain and Ireland. A similarly flourishing trade with the West Indies, chiefly in sugar and tobacco, did not, however, survive the disruption caused by the outbreak of the English Civil War. Within the context of the village, the port played a significant role in the livelihoods of many residents in the 17th century, though not always in a legal manner: smuggling was rife within the Bristol Channel. Buildings such as the fortified Marsh House, built just to the west of the village in 1636, appear to have been used for storage of illegally imported goods, especially tobacco. During the reign of George II, the Master of Fonmon sent soldiers to Aberthaw to try and capture the ringleaders of the smuggling gang. Beyond the business of the harbour, agriculture was also of central importance to the settlement, the land to the east of the village, between East Aberthaw and Fonmon, being marked by windmills and orchards. To the west, the marsh lands were suitable for grazing.