Quillan has two accurate pronunciations: KILL-an and KWILL-an. As an Irish Gaelic boys name pronounced the first way shown it means "cub," and as a variation on the English word name quill, pronounced the second way, it refers to the feather of a bird. Either way, Quillan fits right in with all of the popular names ending with an n.
Quillan also happens to be a town in France that is quite picturesque, as you can see above. As far as namesakes go, Quillan Roberts is a Canadian soccer player, Quillan Isidore is a BMX racer, and Quillan Nagel is a poker player, but none are very well known. In fiction, The Quillan Games is a book by D. J. MacHale, and there is a Star Wars character named Quillan.
Spelled Quillan the name has only been given to boys in the U.S. since about 1982, and although it is now given every year (before 2000 it was given sparingly) it is still incredibly rare - only 9 boys received the name in 2013. It has also been spelled Quillen, Quillon and Quillian, all given far less often.
Quillon, however, is its own name - pronounced KEE-on, KEEL-lon, and KWILL-on (take your pick, as it seems even dictionaries disagree). In Latin it means "sword," and in French and Old German it means "club," from a word referring to a type of bowling pin (ninepin). In U.S. record it was only given once, in 1998, to 5 boys. A quillon is known to be a type of dagger and also the crossguard on a sword, but Quillon is also a city in Chile. As the word for the crossguard of a sword, quillon may have first been recorded in English in 1884 by R. F. Burton in The Book of the Sword.