The actress, who will star as the gender-swapped Ajak in the upcoming Marvel Cinematic Universe film, revealed how "grateful" she was to be cast, admitting that it fills her with "excitement" for the future.
"I was shocked to get that role in my 50s," she told AARP magazine.
"I felt a sense of gratitude and excitement, not only for this but for what it meant about the possibilities for the future."
WATCH: Marvel's Eternals trailer is here
Ajak is the "leader" of the Eternals, a character described as being full of wisdom and maternal to the others, a concept that Salma previously shared with Total Film magazine, admitting that they decided to "tackle the concept of leadership from the perspective of motherhood".
"Instead of just changing the gender, I proposed to [Chloe Zhao, the director] to really bring something that is very specific to womanhood."
Salma and Angelina Jolie will star in Eternals, directed by newly-crowned Oscar winner Chloe Zhao; the film follows a race of immortal beings who lived on Earth and shaped its history and civilisations.
Salma, 55, stars as Ajak, the leader of the Eternals
The upcoming film's official synopsis reads: "Marvel Studios' The Eternals features an exciting new team of Super-Heroes in the Marvel Cinematic Universe, ancient aliens who have been living on Earth in secret for thousands of years. Following the events of Avengers: Endgame, an unexpected tragedy forces them out of the shadows to reunite against mankind's most ancient enemy, The Deviants."
"I think it definitely has its own DNA within the Marvel universe. It is different," Salma previously revealed of the film.
"It was directed by a woman and we didn't do most of the things in the studio. They're real locations which is unusual for Marvel. I'm very excited about the film, it definitely has this special vibe to it that is unique.
Angelina Jolie also stars
"I'm really excited about it and I love my character and I love the cast."
Angelina will star as Thena, Kit Harrington as Dane Whitman, Richard Madden as Ikaris, Gemma Chan as Sersi, and Kumail Nanjiani as Kingo.
Eternals will be released in cinemas in on 5 November 2021
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