Tal-y-llyn, or Talyllyn, is a small hamlet and former parish in the community of Llanfihangel-y-Pennant in Gwynedd, Wales, situated at the end of Tal-y-llyn Lake close to the village of Abergynolwyn. The parish covered an area of 36,000 acres (15,000 ha). The River Dysynni flows out of the lake at this point, flowing down to enter Cardigan Bay north of Tywyn. Another lake known as Llyn y Tri Greyenyn or Llyn Bach was formerly located close to the border with the parish of Dolgellau.