It probably did not need confirmation, but Guardians of the Galaxy filmmaker James Gunn told a fan on Twitter today that, yes, the cameo appearance in which Stan Lee gives a download of important Marvel Cinematic Universe information to the Watchers was inspired by tongue-in-cheek fan theories that the ever-present Lee was, in fact, a Watcher himself. The cameo, which appeared in Guardians of the Galaxy vol. 2, became an instant fan-favorite, and led to more fan theories piling on top of the already-existing ones from whcih Gunn had drawn inspiration for the gag. Lee's final handful of cameos are a little bittersweet now that the legendary comics creator has passed away, but the better ones will no doubt continue to be fans' favorite scenes for years to come.
The conversation spun out of Gunn's tweet earlier today that made a fan theory canon not because it was original intent, but because it was cool, and came from a kid. Another fan replied that more filmmakers should embrace that kind of thing.
"Sometimes, sure," Gunn tweeted back. "For instance, Stan Lee's connection to the Watchers in Vol. 2 was definitely inspired by fan theories."
In the Marvel (comics) Universe, Watchers are the oldest and most advanced race in the cosmos who study lesser races. Most of their job is tied to the education of other peoples, and the most well-known Watcher is Uatu as the being oversees Earth. Prior to Gunn, questions about Lee's potential work as a Watcher had been shot down by other Marvel folks, but Guardians of the Galaxy Vol. 2 decided that it was more fun to embrace the "fanon" than to ignore it.
In Guardians of the Galaxy vol. 2, the team is on the run following a heist when they run into someone who claims to be Peter Quill's biological father -- Ego, the Living Planet. The movie explores the meaning of family and the price of loyalty, and sets up a third and final installment in Gunn's Guardians trilogy that will pick up with the team following the events of Avengers: Endgame and Thor: Love and Thunder.
That movie has not yet begun production, in part because Gunn was briefly fired from the film and, before Disney hired him back, he got a job writing and directing The Suicide Squad for Warner Bros., which is currently in post-production. Guardians of the Galaxy vol. 3 is expected in theaters in 2022 or 2023.