| Country: | Wales |
| Welsh Name: | Llandysilio-yn-Iâl |
| Official Name: | Llantysilio |
| Community Wales: | Llantysilio |
| Unitary Wales: | Denbighshire |
| Lieutenancy Wales: | Clwyd |
| Constituency Welsh Assembly: | Clwyd South |
| Constituency Westminster: | Clwyd East |
| Population: | 421 |
| Population Ref: | (2011) |
| Post Town: | LLANGOLLEN |
| Postcode District: | LL20 |
| Postcode Area: | LL |
| Dial Code: | 01978 |
| Os Grid Reference: | SJ1943 |
| Coordinates: | 52.983°N -3.203°W |
| Static Image: | Llantysilio - Valle Crucis Abbey.jpg |
| Static Image Width: | 240px |
| Static Image Caption: | Valle Crucis Abbey |
Llantysilio (Welsh: Llandysilio-yn-Iâl) is a community in Denbighshire, Wales, near Llangollen. It has a population of 472,[1] falling to 421 at the 2011 census.[2]
The community includes the site of Valle Crucis Abbey, the Horseshoe Pass, and Llantysilio Hall; it also includes the villages of Pentredwr and Rhewl, as well as the areas of Eglwyseg, Llandynan, and Llidiart Annie.[3]