The default user when you install WordPress is called “Administrator” and many people don’t change it which unfortunately leads to anonymous looking posts made by Administrator instead of by Matt, Mark, Lloyd, Joseph, Alex or your own name of course.
I would venture to say it’s a new user problem but I remember seeing Administrator posts by old hands at the blogging game so it might be worth double checking, just in case. Your template might not show Administrator, but your RSS feed isn’t as clever.
It’s simple to check and fix. Log in to your WordPress blog, go to Users, and then Your Profile. If you haven’t changed your first and last names, do it now. Click “Update Profile” and then change your “Display name” to a friendlier name.
One final tip, it’s probably much safer to blog as a non-admin user. If you’re logged in all the time, consider creating an editor or author user. If you leave your laptop unattended in a busy area for a moment it’s much less likely that someone will do real harm to your blog. (Presuming they don’t rob the laptop first!)
If you’re a WordPress.com user, then don’t worry about Administrator showing up on your blog posts, it won’t happen as your login name is your author name. Isn’t that nice?
"WP Tip: don't blog as Administrator",