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 ab 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