Robert Downey Jr's letter that he wrote after his last outing as Iron Man goes viral

Robert Downey Jr, who has famously played Tony Stark aka Iron Man, in the Marvel Cinematic Universe (MCU) for almost a decade, wrote a parting letter to the franchise in 2018 that has now gone viral. 

The letter was published in a special tie-in book titled The Story of Marvel Studios: The Making of the Marvel Cinematic Universe by Tara Bennett and Paul Terry, which released last week, according to The Indian Express. 

Downey Jr first made an appearance as the superhero in Iron Man (2008). He then reprised the role in films like The Avengers, Avengers: Age of Ultron, Iron Man 2, Iron Man 3, Spider-Man: Homecoming, and Avengers: Infinity War. His last outing was in 2019's Avengers: Endgame.

The actor wrote about being cast in the role, and how Jon Favreau was sure of the film's success. He also praised his fellow MCU stars Chris Hemsworth (Thor) and Chris Evans (Captain America), writing that it was their invovlement that made the Avengers franchise popular. 

"I hope these films have evoked a dialogue on equality, justice, freedom, embracing diversity, and combating intolerance with the power of partnership, sacrifice, and love. At this point, Tony might say: 'You’re welcome.' I’ll balance that with a boundless eternal: 'Thank you'," wrote the actor, as quoted by Express via The Direct.

Downey Jr gave a shoutout to Black Panther director Ryan Coogler and the late actor Chadwick Boseman, calling him "the most reflective and grounded frontman of the bunch."

After leaving the Marvel universe, Downey Jr has several upcoming projects including a third Sherlock Holmes film, a sports comedy All-Star Weekend, and an adaptation of the novel The Sympathizer.