I'm really sorry to have to do this, but there's always someone out there who won't listen any other way. So here is the legal mumbo-jumbo.
I am the legal copyright owner of the characters I create, including (but not limited to) the characters described on this site. In order to remain that way, I have to protect my rights.
If you are an artist, you may draw my characters subject to these rules. Drawing my characters expressly signifies your acceptance of the terms therein. And just to be clear, you really do need to ask first, please.
I know that copyright notices upset some people, so please let me explain. I'm not a jerk and I don't wave the word "copyright" around to be offensive. But the fact is, there are a very small minority of people out there who don't get basic etiquette, and the only way to get their attention is with a baseball bat. I'll probably be thrilled if someone wants to draw my characters. I just don't want to wake up one morning and open my web browser to see one of my characters humping a hippopotamus or something. No offense intended to any hippopotami who read this.