Seisyll or Seisyllt is a Welsh male given name. It may refer to: * Kings

Sisillius I Sisillius I ('' Welsh:'' Seisyll) was a legendary king of the Britons as accounted by Geoffrey of Monmouth Geoffrey of Monmouth (; ; ) was a Catholic cleric from Monmouth, Wales, and one of the major figures in the development of British hi ...

and II, legendary kings of the Britons *

Seisyll ap Clydog Seisyll ap Clydog was King of Ceredigion in Wales some time in the late 7th or early 8th century. He gave his name to the later kingdom of Seisyllwg, which consisted of Ceredigion plus the region known as Ystrad Tywi; as such he was possibly the ...

(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