Gaerllwyd () is a village in the community of Shirenewton, in Monmouthshire, south east Wales.
Gaerllwyd is located south east of Usk and north west of Chepstow on the B4235 road.
Gaerllwyd is set in a very rural agricultural area in the heart of Monmouthshire. There is a Neolithic burial chamber, or cromlech dated to around 4,000 BC. It is made up of a capstone which would have had three upright stone supports. The outer cairn has been removed by road construction and stone robbing, although archaeologists are uncertain whether a covering mound would ever have been in place. To the south there are some Early Bronze Age monuments including two stone circles, a standing stone and a round barrow cemetery.
The village has a Baptist chapel, situated on the Gaerllwyd Crossroads, which is still in regular religious use. It is a Grade II listed building.