Snodhill Castle is a ruined motte-and-bailey castle, about 1 mi (1.6 km) south of the village of Dorstone in west Herefordshire, England. It is recognized as one of the major castles of the Welsh Marches. It was built in the 11th century to secure the border between Norman England and the Welsh Princes. Archaeological excavations show that it was one of the first Norman castles in England to have stone-built fortifications, with more sophisticated defences being added in later centuries.

The castle was first referenced in 1142. Although it was recorded as being in decay in the mid-16th century, it was thought to still be in use during the 17th century. It remained in private hands until 2016, when it was acquired by a charitable trust backed by Historic England to preserve the remaining structure.

The origins of the castle are unknown, but there are two theories about its creation: one, that it was built by a follower of William FitzOsbern, 1st Earl of Hereford before 1086 and two, that it was built by Roger de Chandos after a land exchange with Malvern Priory in 1127. However, both theories are debatable, due to recent archaeological investigation finding a very early stone hall keep buried beneath (and incorporated into) the existing multiangular keep on top of the motte (the motte dating from 1160). Further investigation found similarly early curtain walls defining a small triangular bailey. These discoveries have led to re-evaluation of the castle's early history. It is now thought that the castle did not have an initial timber phase, and that it was built in stone from its foundation in 1067 by FitzOsbern, and completed before his death in 1071. He is known to have built other early stone castles, Chepstow Castle being the most famous, with stone defences at Monmouth Castle, Clifford Castle and Wigmore Castle supposedly built by him as well.

Snodhill Castle was then granted to Hugh L'Asne before FitzOsbern's death in 1071, the whole border area from Chepstow to Shropshire having been parceled up and granted by the Earl to his close supporters. The castle was held by Hugh L'Asne until his death in 1101 when it, and all of Hugh L'Asne's manors, passed by marriage to Robert de Chandos I.

The castle was held and further developed by the Chandos family until the 15th century. In 1401, John Chandos was ordered by Henry IV to refortify his castle against the Welsh Revolt of Owain Glyndŵr. Chandos obeyed the king by building a large tower in the castle's main bailey (acting as a second keep) and thickening the bailey cross-wall. These additions resulted in Snodhill Castle not being destroyed during Owain Glyndŵr's attacks on Herefordshire. Chandos died without an heir in 1428 and his holdings were inherited by the Beauchamp family, relatives of his wife. It was briefly held by Richard Neville, 16th Earl of Warwick, known as "Warwick the Kingmaker," and then, through the marriage of Anne Beauchamp, passed to Richard of York (later Richard III). Following this, it became a royal castle.

In 1540, the area was visited by the antiquary John Leland who described the castle as follows:

There is a castell a mile and more benethe Dorston apon the right ripe of Dour. It is called Snothil, and ther is a parke wallyd, and a castle in it on a hill caulled Southill, and therby is undar the castle a quarrey of marble. The castle is somewhat in ruine. Ther is a Fre Chappell. This castle longyd to Chandos.

Elizabeth I granted Snodhill, along with other Warwick holdings, to Robert Dudley, 1st Earl of Leicester. Some sources state that the castle was besieged during the English Civil Wars, Evidence has been found for both slighting of the keep and organized demolition after the civil war. By the mid-17th century, the manor and castle had gone into the hands of the Prosser family and their relatives, the Powells, who held the property until it was sold in 1940.