Chwilog is a village in Gwynedd, north Wales, and located on the Llŷn Peninsula. It is in the community of Llanystumdwy, near Criccieth, and in the medieval commote of Eifionydd, named after a 5th-century ruler. It is within the Dwyfor Meirionnydd constituency in the UK Parliament and in the Senedd. The name means 'abounding in beetles' and was perhaps transferred from an earlier name of the river.