Stan Lee Is A Watcher
Legendary comic book creator Stan Lee has been a mainstay of the Marvel Cinematic Universe since 2008’s Iron Man, appearing in every single installment of the franchise for a brief but fun cameo as a variety of characters. Seeing as the rest of the MCU was so keen on keeping everything connected, though, fans devised a way that Lee’s appearances could be counted as the same character.
They drew from the comics and came up with the idea that he was playing either a Watcher in disguise or at least an informant for them. The Watchers are ancient aliens from the Marvel universe that are sworn to view but never interfere. For instance, Uatu the Watcher was particularly interested in watching the activities of Earth’s heroes. As the rights to Uatu rested with Fox though, it was thought that Lee was effectively the MCU version of the character.
In Guardians of the Galaxy Vol. 2, this theory was finally made canon when Lee’s cameo on this occasion saw him chatting to the Watchers in space, regaling them with a tale about the time he was a FedEx man, a reference to Captain America: Civil War. It seems this was director James Gunn’s idea, but Marvel president Kevin Feige supports it and says it was intended to be a confirmation that all Lee’s cameos are connected.