Llandysilio 1 is a roman-letter inscribed stone, first noted in 1745 in the churchyard of St Tysilio's Church, Llandysilio (NPRN 308656). It was built into the external south wall of the church (near the east end, just above ground-level) in 1838, along with two other inscribed stones and a cross-carved stone.

The stone is a dolerite boulder. Measurements are given as 105.5cm height x 94cm width max, but the stone is thought to have originally been considerably taller. Only face A is visible and parts of the inscription have been damaged by lamination. The Latin inscription is thought to date to the later 5th or early 6th century. It has been translated as `of Clutorix son of Paulinus Marinilatio?.

Sources include:
Edwards, N. 2007, Corpus of Early Medieval Inscribed Stones and Stone Sculpture in Wales

N Vousden, 3 January 2018