Llanystumdwy (Welsh pronunciation: [ɬanəstɪmdʊɨ̯]) is a predominantly Welsh-speaking village, community and electoral ward in the Eifionydd area of Gwynedd in Wales.

The village lies on the southern coast of the Llŷn Peninsula, with a beach facing Cardigan Bay, between Criccieth and Pwllheli at the point where the A497 road crosses the Afon Dwyfor.

The art-deco Lloyd George Museum, another of Williams-Ellis' creations, is also in the village and features artefacts from the politician's life, an audio-visual theatre and a Victorian schoolroom.

Often mistaken for Bont Fechan, which stands a mile away by a garden centre of the same name, it is claimed that the initials D LL G carved clearly into the downstream bridge parapet are the work of David Lloyd George himself.

Other buildings of note include the Tafarn y Plu (also known in English as "The Feathers"), the institute or village hall known as Neuadd y Pentref, which was financed by Lloyd George with compensation he received having won a libel case, the 19th century St John's Church, and the Moriah Methodist Chapel.