Nylan is a character from the fantasy book series "The Saga of Recluse" by L. E. Modesitt, Jr.. Specifically, the book "Fall of Angels".
I've been using it, along with the number sequence, as my online alias since I was very young.
'83 was the year I was born. '01 was the year I graduated high school. Both parts of the alias aren't very imaginative, I know, but I like them.
Oh, and don't read "The Saga of Recluse" unless you like formula writing where every book is essentially the same, but with different characters and slightly differing plot. I grew to hate this series about ten books in. The beginning is quite good, but it gets very stagnant as time goes on.