Castellan is an ancient hamlet and, until 1974, was a parish in the Hundred of Kilgerran, Pembrokeshire, Wales.

It was originally a chapelry of the parish of Penrydd (several alternate spellings), granted by William Marshal, Earl of Pembroke, to the Knights Hospitallers of Slebech c.1130 and was returned in the Valor Ecclesiasticus (1291) as paying 13s 4d (two-thirds of a pound) per annum.

[2] In 1684 the rector and churchwardens of Penrith (sic) and Castellan declared the chapel to be "out of repair", the bier having been stolen some 28 years previously.

Prior to 1850 the parish included Blaenffos, Clover Hill, Frenni Fawr, Gorsfaith and Moelfryn with a population of 127 in 1833; earlier censuses included Castellan with Penrith[9][10] and formed an extensive part of the parish of Penrith (sic).

The name of the parish survives in Castellan Farm, near the site of the chapel which, according to Geograph,[15] is no longer accessible.