- Source: Seisyll
Seisyll or Seisyllt is a Welsh male given name. It may refer to:
Kings Sisillius I and II, legendary kings of the Britons
Seisyll ap Clydog (late 7th century), a king of Ceredigion
Seisyll ap Rhun (10th century)
Seisyll ap Ednywain or Owain, father of King Llywelyn of Gwynedd
Seisyll ap Dyfnwal (12th century), a lord of Upper Gwent
Seisyll Bryffwrch (12th century), a poet
Seisyll ap Rhun Fychan (13th century)
See also
Selyf, a variant of the same name