Stan Lee is known not only for his celebrated superheroes but also for his creative cameos in various Marvel films and TV shows. From a mailman to a security guard, Lee has played a small role in nearly every one of the Marvel films between 1989 and 2018.

For years, fans have debated whether Lee's 15 seconds of fame are just for fun or if they hold a greater significance to the Marvel franchise. Guardians of the Galaxy Vol. 2 supports a fan theory that Lee's background roles actually have a bigger meaning in the Marvel Cinematic Universe. In the movie, Lee can be seen talking with cosmic beings called Watchers, on a barren planet about his time as a delivery man on Earth. It turns out, Stan Lee has been playing the same character in all of his movies, and may even be a Watcher.

"Stan Lee clearly exists above and apart from the reality of all the films, so the notion that he could be sitting there, on a cosmic pit stop, during the jump gate sequence in Guardians, was something very fun," Marvel Studios head Kevin Feige said in an interview, noting that at one point the scene was cut from Guardians, before being added back in. "We thought it would be fun to keep that in there because that really says, 'So wait a minute, is this the same character who’s popped up in all these films? Is this the same person?'"

The Hollywood Reporter takes a look at 40 of his cameos over the years.