Source: USA Weekend
Idris Elba who is most known for his role as Stringer Bell in The Wire is currently starring in Takers, a heist film opening this weekend.  He talked about Takers and Thor in USA Weekend.   Here is an excerpt from that interview:
You just finished your stint filming Thor as the Asgardian warrior Heimdall. How was that?
It was dope. It was an interesting genre of film to make. I had never done comic book stuff, so that was really great.
What was the coolest part?
Just the bigness of the show. It’s so epic, these huge sets were just amazing …

Source: Superhero Hype
Idris Elba was cast as Heimdall, the Asgardian who stands guard on the BiFrost Bridge.  He joins Chris Hemsworth, Tom Hiddleston, Natalie Portman, Sir Anthony Hopkins, Colm Feore, Samuel L. Jackson, Stellan Skarsgard, and Stuart Townsend.
I think this is great. Elba is one of the premiere black actors and doesn’t get nearly the pub that he should.  He would’ve been my pick for any numerous black superheroes, but this is a perfect role for him. Props to Marvel for making this move.