Rhun ap Maelgwn Gwynedd (died c. 586), also known as Rhun Hir ap Maelgwn Gwynedd (), sometimes spelt as 'Rhûn', was King of Gwynedd (reigned c. 547 – c. 586). He came to the throne on the death of his father, King Maelgwn Gwynedd. There are no historical records of his reign in this early age. A story preserved in both the Venedotian Code and an elegy by Taliesin says that he waged a war against Rhydderch Hael of Alt Clut and the kings of Gododdin or Manaw Gododdin. The small scattered settlement of Caerhun in the Conwy valley is said to be named for him, though without strong authority. Rhun also appears in several medieval literary stories, as well as in the "Welsh Triads". His wife was Perwyr ferch Rhûn "Ryfeddfawr" and their son was Beli ap Rhun "Hîr".