Trefignath is a Neolithic burial chamber near Trearddur, south of Holyhead on Holy Island, off Anglesey in Wales.

In its most complete form it included a large cairn covering three stone tombs, set on a small knoll.

At this stage deciduous forest covered almost all of the land area, and this would have developed a deep, rich, and well-drained soil.

Pottery sherds left before the building of the tomb were un-decorated Irish Sea ware of the early and middle Neolithic.

It had a simple, square chamber, with an entrance facing north-west, and was covered by a circular mound of stones (a cairn).

William Owen Stanley in 1867 states that the monument had been further damaged about 1790, when the capstones were removed, to be re-used as gateposts and lintels.

Complete destruction had only been avoided by the intervention of Stanley's grandmother Margaret, heiress to the Penrhos estate which included the site.

[5] In 1856 a visitor made extravagant use of the ideas of the Celtic Revival to imagine Druids using the location for human sacrifice: "Here the Druid priests once offered their dreadful sacrifices, and performed their idolatrous worship, in their long white garments, their temples enwreathed with chaplets of oak-leaves, the magic wand in their hand, and on their head a serpent's egg, an ensign of their order; thus attired they went forth to sacrifice, standing round the crimson-stained altar, shrouded with superstition, mystery and death.

Here the victims, bound with cords for slaughter and sacrifice, filled the air with shrieks of agony and screams of horror...

Here once lived and worshipped another race of beings, who from their forest haunts came forth in mystic power to invoke their awe-throned deity with human sacrifices.