2021 marks an interesting anniversary: it marks the point when TSR’s been dead and buried for longer than its original lifespan (1973-1997, a run of 24 years). From this year onwards, Wizards of the Coast will have been in control of D&D for longer than TSR ever was.
Perhaps coincidentally, perhaps not, Shannon Appelcline of Designers & Dragons fame just posted an interesting RPG.net column documenting the various infamous legal entanglements of TSR over their lifespan. What’s particularly interesting is the evolution over time; at first, TSR were actually being pretty co-operative, and there’s a possible alternate universe where they continued to play nice with licensors all through their lifespan, much as Chaosium have over the years. (Whether they survived longer in that universe or not is a different question.)
It was only later when they started burning bridges and getting more ruthless in their business practices that they started attracting legal disputes – and then got more aggressive. When I came into the hobby, Internet wags’ second-favourite nickname for TSR (after “T$R”) was “They Sue Regularly”, stimulated in part by the company’s utterly needless (and legally baseless) own goals when it came to aggressively going after fansites posting homebrew material. The article’s pretty decent at covering this history – check it out.