Lee has appeared as everything from a bus driver to a librarian alongside the comic book characters he created over the years.
But sincein 2018, it's been unclear how many more posthumous cameos would be granted to the late, great comic book creator, until now.
"It's his last one committed to film," Avengers: Endgame director Joe Russo told the media on press day in Los Angeles Saturday.
Some fans speculated that the upcoming Spider-Man: Far From Home, which hits theaters in July, would feature Lee's final cameo, especially since Russo told the press earlier this month that "I don't remember if he was well enough to do the cameo in Homecoming or not."
While it's bittersweet to learn that Lee's last hurrah in the MCU is coming up fast, the for the upcoming movie could mean that Marvel might give Lee more than one appearance in the three-hour movie.
"I have to say, I think it's astonishing that this would be his last cameo," Russo added. "It's just kind of mind-boggling that he made it to the end of this run. I can't believe it."
After all, discussing his past adventures with various interested aliens referred to as the Watchers.allowed for not one but two moments in the film where Lee -- dressed as an astronaut -- is seen
For more Avengers: Endgame plot theories, characters reveals and news check out our Avengers: Endgame movie guide.
If you want to catch every Lee cameo in the MCU movies before the Endgame begins, here's.
Originally published 2:36 p.m. PT.