The first domain name ever registered was Symbolics.com.
(Seemingly nordu.net was used for the first ever root server (nic.nordu.net). So, it was techinically the first ever domain name, as it was created by the registry (for use by the registry) on day 1, before domains were even allowed to be officially registered. But, Symbolics holds the distinction of being the first ever registered name. What’s really interesting is to see what they’ve done with the web site. http://www.symbolics.com/)