Thor: Ragnarok features Idris Elba's Heimdall in his biggest MCU role yet, but even that doesn't change the fact that the God of Thunder's solo movie series wasted one of the greatest talents working in Hollywood today. Elba first signed on to play the character back in late 2009, a few years removed from his breakout turn in The Wire and shortly after filming the first season of the acclaimed BBC crime drama, Luther. He wasn't exactly an A-lister back then, but the part still seemed pretty small for an up and coming star like Elba. He later revealed that he decided to ink the four picture deal after receiving a call from director Kenneth Branagh, who was also cited as the main reason Natalie Portman agreed to play Jane Foster. "This is a man that called me up personally and said, 'I know this isn’t a big role, but I would really love to see you play it'", said Elba. "It’s Kenneth Branagh. I was like, 'Definitely.'" But still...Heimdall??
In the pages of Marvel Comics, Heimdall is the all-seeing and all-hearing Asgardian tasked with guarding the Bifrost bridge, the gateway between Asgard and the other eight known realms. All things considered, he's rarely been depicted as a vital character. He's Sif's brother (that bit wasn't translated into the MCU), he was once temporarily granted the Odinpower in order to rule over Asgard, and he once was seen using his near-omniscience to track down the scattered souls of Asgardians on Earth following a particularly devastating Ragnarok cycle. Other than that, honestly, there's just not a hell of a lot to the guy.
Heimdall was never a character that ever had much of a shot of being any more than what he ultimately became in the Thor series: a secondary character that would always be left in the dust while the titular hero was off saving the day. But Marvel's never had any problems making changes to the source material while bringing their comics to the big screen. They've certainly beefed up characters' roles based on audience reaction before, and if there's an actor on their roster who is deserving of a beefed up role, it's Elba.
"This is torture, man"
For reference: here's a quick refresher of Heimdall's actions in the Thor trilogy: he features in a handful of scenes in each of the first two films, before being granted an expanded role in Ragnarok (albeit one that has him doing the bulk of his actions offscreen). During those first two outings, Heimdall betrays the realm on three separate occasions by allowing people through the Bifrost when his king had expressly ordered him not to. And despite his near-omniscience, during The Dark World, a Dark Elf invasion of Asgard passes right under his nose. He does manage to save hundreds of the realm's citizens during Hela's takeover in Ragnarok, but overall, not only does Heimdall have a minor part to play in all three films, but he's not even depicted as being particularly good at his job.
Moderate expansions in the role over the course of the trilogy reflect that Marvel was clearly trying to work Heimdall in more, especially after Idris Elba's star power grew and he became a household name. But the actor was still understandably frustrated with his limited role, and he wasn't shy about sharing these frustrations in an interview with The Telegraph back in 2014. After venting about being pressured to do a cameo for Avengers: Age of Ultron, Elba got super candid about just how much he was enjoying his time as Heimdall:
It was really weird. I’d just done eight months in South Africa. I came to England and the day I came back I had to do reshoots on Thor 2. And in the actual scene my hair was different, my...I was like, ‘This is torture, man. I don’t want to do this.’ My agent said: ‘You have to, it’s part of the deal.’ [In the scene] I’m actually falling down from a spaceship, so they had to put me in harness in this green-screen studio. And in between takes I was stuck there, fake hair stuck on to my head with glue, this fu***** helmet, while they reset. And I’m thinking: ‘24 hours ago, I was Mandela’ ... Then there I was, in this stupid harness, with this wig and this sword and these contact lenses. It ripped my heart out.
And somehow, folks, it gets worse.