UNIX copyrights
As is well known , UNIX came from AT&T, but after the telco breakup, they unsuccessfully tried to market their own computers (I was there late 80s..), and eventually joined forces with Novell to create Unixware and Unix System Labs (visited the Summit NJ site a few times), then eventually sold their half *to* Novell (Dennis Ritchie quoted the OT verse about Esau selling his birthright at the time; RIP sir...).
Santa Cruz Operation was an ISV that did an x86 port of the legacy-AT&T code; when Novell began to flounder in the wake of WinNT, they tried to buy out the copyrights but couldn't come up with the cash; Novell gave them the business of collecting the royalties from all the other licensees and keeping a 5% admin fee.
Linux started eating the *ix-on-Intel market, Santa Cruz did a deal with IBM to port UNIX to Itanium (Itanic...) which went nowhere. It was then bought out by a Novell spinoff Caldera, which rebranded itself as SCO. IBM invoked the buyout clause of their joint contract to take their code & walk. It eventually ended up in AIX, along with some code from Sequent etc.
SCO/Caldera continued to flounder, then decided to sue IBM for infringement despite the techs telling the suits there was nothing to go after. It's dragged on for years now, and Xinuos eventually bought out the dwindling software business and left the bankruptcy trustee to continue the lawsuit. Apparently they haven't had any better luck in the market and opened their own case a few years back claiming infringement. They haven't had any better luck. Hopefully the Nazgul Horde will shortly eliminate them once and for all.