Mine has a long and storied history. :P
It started off as one of two main characters in a short story I wrote about 18 years ago, and was planning on turning into a book. Well, that never went anywhere. But 13 years ago, when I first started on IRC, I took one of those two names, "Taryl", and used it as my IRC nick.
We all know how IRC is, and after a d/c when my old nick was still on as a ghost connection, I shifted it to Taryble. Started joking about being the "Taryble Twentysomething Texan", or the "Taryble Texan". So the Taryble ended up sticking around a lot longer than anything else did.