Llantysilio (Welsh: Llandysilio-yn-Iâl) is a community in Denbighshire, Wales, near Llangollen. It has a population of 472, falling to 421 at the 2011 census.

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.