Watch: Richard Madden discusses being Marvel's first Scottish hero
The 35-year-old Renfrewshire-born actor plays the all-powerful Ikaris — capable of flight and firing energy beams from his eyes — in Chloe Zhao's movie, and was able to use his natural accent for the part.
"That was something we discussed at the start of the film," Madden told Yahoo.
He added: "With everyone being so diverse and all of the different accents in there and thinking 'let's keep this as all of these different textures and colours'. I kinda like it. The original Scotsman."
Madden's character is the first Scottish hero in the MCU, though Maisie Williams deployed a north-of-the-border accent as Wolfsbane in the Marvel-adjacent X-Men movie The New Mutants last year.
Ikaris's impressive array of super-powers make him one of the most eye-catching characters in the film, but it led the actor to take on some challenging days on set.
Read more: On set with Eternals at Pinewood Studios
Madden said: "It's very fun when you see [the flying scenes] at the end. During filming, it's a lot of work.
"It's a lot of hours in these harnesses and wires, but it's cool when they hoist you up to three storeys high and they swing you in and drop you down and you wrestle a big, green-screen duvet.
"But in the end, the VFX guys make it look super cool and I'm like 'okay, it's worth all the pain'."
Eternals is one of the most diverse films in the history of the MCU, introducing the studio's first deaf hero — Lauren Ridloff as the super-speedy Makkari — and the first openly gay superhero in Brian Tyree Henry's tech supremo Phastos.
Behind the camera, the film boasts the Oscar-winning clout of Chloe Zhao, who took to the stage of the Academy Awards earlier this year to win a handful of prizes for Nomadland.
Zhao has said she was given complete creative freedom by Marvel when she took on the movie, adding that she "got lucky in that Marvel wants to take risks and do something different".
Eternals zooms into UK IMAX and cinemas from 5 November.
Watch: Trailer for Marvel blockbuster Eternals