What's up with the name Llewyn? I recently saw the film Inside Llewyn Davis and, like many name nerds, I was interested in the name Llewyn. I had never heard it before, so I did some digging. Llewyn. It looks like a real Welsh name. In the film, the character of Llewyn Davis also admits it's Welsh. In one scene, another character, Roland Turner asks, "what does the N. stand for [meaning Lou N. Davis]?" and David replies "Llewyn. It's Welsh."
Makes sense. It's contains common elements in Welsh names. Llew meaning "lion" found in the name Llewelyn (which was actually originally Llywelyn formed from llyw meaning "leader" and then altered to contain llew meaning "lion") + -yn which can either be just a diminutive ending, or a truncated form of -gwyn, which is the masculine form of a common Welsh element in names that means "white," but also came to mean "shining; radiant; pure; or holy."
However in my searches, Llewyn in that form, didn't show up in any of my Welsh name books. In fact, pretty much the only searches that came up for this name were for this movie, plus a small handful of people with the name (male, female and surname; most of them seem to American, but my search engine is probably biased to American results).
Did the Coen Brothers invent this name for the movie? Probably not. My guess is that this is a modern name, probably coined in the late 19th-early 20th century. Several Welsh names were coined in this period, such as Glynis/Glenys, & Glenda. *I have no proof of this, just a gut instinct.* There was a resurgence of interest in Welsh names during this period, and many historic and mythological names that had lain dormant for centuries were brought back out again (such as Rhiannon and Dylan), or got a modern facelift and started being used, such as Gwyneth (possibly started out as Gwynedd or Gwenith).
Of course, being the Internet, people are going to now start sending me hate mail and tell me that I'm wrong and that I'm stupid and should be hanged for treason etc., so by all means, if you know the answer, let me know! Getting Welsh name books in the USA isn't always easy!