Anyone who follows the Marvel movies knows that Stan Lee has had a cameo in every superhero adventure, dating back to the little-known 1989 feature The Trial of the Incredible Hulk, all the way up through last month's Guardians of the Galaxy. He even appeared in an episode of ABC's Marvel's Agents of S.H.I.E.L.D. earlier this year.

Out of all these appearances, Stan Lee was recently asked on Twitter which cameo was his favorite, which he revealed is a role fans haven't seen yet, in next year's Avengers: Age of Ultron.

Some are speculating that his phrase "worth waiting for" may have a double meaning. It most likely means that it's worth waiting the eight more months until the Marvel Phase Three sequel hits theaters, but others are speculating that his cameo may come in an end credit sequence. Marvel has been using two credit scenes in recent movies, one while the credits are rolling and another at the very end, so it's possible that Stan Lee's appearance may be in one of possibly two end credit scenes in Avengers: Age of Ultron.

It's also possible that his cameo may change. It happened in 2012's Marvel's The Avengers, when his scene with Captain America (Chris Evans) was cut after the focus of the movie changed, and in last month's Guardians of the Galaxy, where the Marvel universe creator was originally supposed to be discovered in the Collector's museum instead of as an intergalactic playboy targeted by Rocket Raccoon.

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Which Stan Lee cameo is your favorite? Chime in with your thoughts below.