Part of Project Athena at MIT in the 1980s.  Not sure when the logo happened, but almost certainly it'll be owned by either The Open Group, or the X.org Foundation today.
It's likely, however, that it'll be under an MIT-style license, so a moderately difficult prosecution of its rights if anyone wanted to.
-Adam

Get Outlook for Android
From: Roundtable <roundtable-bounces@muug.ca> on behalf of Trevor Cordes <trevor@tecnopolis.ca>
Sent: Tuesday, July 25, 2023 4:39:29 PM
To: roundtable@muug.ca <roundtable@muug.ca>
Subject: Re: [RndTbl] X.com vs X.org logos
 
I'm sure someone originally "owned" X.  AT&T?  Oldsters (well older than
me!) will know.  They, and then the companies who merged with them or
bought them out, would probably own the logo trademark.

The logos are similar enough, and they are both in the realm of
"computers", therefore there may be issues.  But if no one really cares
about the X logo anymore, whoever owns it should sell it to Elon and
make mega-bank!  If this benefits the community (Xorg) somehow, then
bonus.
_______________________________________________
Roundtable mailing list
Roundtable@muug.ca
https://muug.ca/mailman/listinfo/roundtable