DeadlineHollywood reports that Natalie Portman may possibly join the cast of Thor, likely in the role of Sif, Thor's wife.
Who would play opposite Portman as Thor is still undecided, and it looks like rumored Kenneth Branagh favorite Alexander Skarsgård has some competition. Charlie Hunnam (F/X's Sons of Anarchy), Tom Hiddleston (Branagh's co-star from in the Masterpiece series Wallander), Liam Hemsworth (Knowing), and Danish actor Joel Kinnaman (Danish movies) are all being tested for the movie. Most of the actors are unknown because, according to a source, there is a "powerful lobby" that wants an unknown cast as Thor.
There's even less time for casting decisions, as Thor's release date has been changed again, this time to May 20, 2011, two weeks after Spider-Man 4.