[Hopefully I will now manage to forward this reply to the _right_ mailing list - my first attempt to contribute to the Wiki mailing lists wasn't too successful!]
In message 20030507205434.GD5102@jeluf.mine.nu, Jens Frank JeLuF=Mmb7MZpHnFY@public.gmane.org writes
Hello,
A new user registered a few days ago using the name "Harry Potter". Warner Bros and JK Rowling have a trademark registered for this name.
On the new users talk page ( http://www.wikipedia.org/wiki/User_talk%3AHarry_Potter ), MammaBaer posted some concerns about the user name and its legal status. I'm not experienced in trademark law, so I post this to the list.
Is the use of a trademarked name as a username problematic?
I wouldn't have thought so if he doesn't try to engage in wizardry. It may conceivably even be his real name. Even as apparently unusual a name (in an English-language context) as my own is not unique, as I know I have had a rugby-playing namesake which used to result in some strange newspaper headlines appearing on the office noticeboard on a Monday morning! :)
Arwel Parry