Llanfair-Mathafarn-Eithaf (Welsh pronunciation: [ˌɬanvair maˈθavarn ˈei̯θav]) is a parish and community in Anglesey, Wales including the small seaside town of Benllech.

[1] Local buildings include the medieval St Mary's Church, where the 18th century poet Goronwy Owen once served as curate.

The parish has five Scheduled Monuments, including two collections of hut circles and the stone remains of a dolmen type Neolithic burial mound, called the Pant-y-Saer Cromlech.

The parish lies on an area of Carboniferous Limestone and supports a variety of wildlife, including red squirrels.

The Cors Goch nature reserve is a rich fenland habitat in the west of the parish and is designated an SSSI.