| Country: | Wales |
| Official Name: | Llandyfaelog Fach |
| Unitary Wales: | Powys |
| Lieutenancy Wales: | Powys |
| Postcode Area: | LD |
| Postcode District: | LD3 |
| Post Town: | Brecon |
| Coordinates: | 51.9794°N -3.4105°W |
| Static Image: | St. Maelog's church, Llandefaelog - geograph.org.uk - 927002.jpg |
| Static Image Caption: | St Maelog's Church |
Llandyfaelog Fach (or Llandefaelog Fach), is a small village and community located in Powys, Wales. It includes the surrounding areas of Glan Honddu, Sarnau, Pwllgloyw and Garthbrengy. These areas border the village. The nearest pubs and shops are in Brecon. Cradoc golf course is also nearby.
The village has a church dedicated to Saint Maelog. The church contains the Cross of Briamail, known as in Welsh.
In the churchyard are the remains of a striking 1816 mausoleum in Egyptian style for the owners of the nearby Penoyre estate. This has largely collapsed recently but previously black lead coffins were visible through its iron barred windows.