Llywelyn

In the MMORPG Mabinogi, there is a character named Llywelyn. He's how I learned about this name and he's one of my most favorite characters :)

In Shakespeare's play Henry V, there is a Welsh character named "Fluellen." This is an anglicization of this name, the "fl" being an attempt to reproduce the voiceless "ll" sound of Welsh.

In D.C. Simpson's comic "Ozy and Millie", Ozymandias Llewellyn and his father (just known as Llewellyn) are sovereign rulers of Llewellynland (ie: their house and yard). Llewellyn is a dragon and therefore responsible for many of the world's conspiracies.
http://www.ozyandmillie.org.