Saint Sulien, Sulian, or Silin was the reputed 6th-century founder-abbot of a monastery at Luxulyan in Cornwall. His feast day is 29 July.
There have probably been other Christian Celtic saints with the same (or similar) name, and a variant of it is also used as an alias of Saint Tysilio (see below).
Sulien is a Welsh variant of the given name "Julian," but has also been interpreted as being derived from the Welsh sul, meaning "sun" + geni, meaning "born," Sulien being the name of a Celtic solar deity.
Confusion has arisen between different legends of Celtic saints with the name Sulien (in a variety of spellings). The three most commonly encountered are:
The first two, who originate from the Celtic states in broadly similar historical context, may be the same person. However, the fact that separate feast days have been assigned to them from antiquity is strong evidence that they are different people, and that there were in fact three different Celtic saints with the same (or similar) name.