UPDATE: Screenrant (via Vulture) report that one character we won't be seeing in Iron Man 3 is Scarlett Johansson's Natasha Romanoff. Johansson did share her hopes that Marvel might spin Black Widow a movie of her own, so fans of the catsuit-clad mysterious Russian butt-kicking superspy should watch this space.

With shooting set to launch next month under the watchful eye of co-writer-director Shane Black, Iron Man 3 is locking in more cast members. Ben Kingsley and Guy Pearce are already either aboard or close to a deal, but now the film looks set to get even more thespian power in the form of Jessica Chastain.

The actress – who has appeared in all the films last year, including The Tree Of Life, The Debt and The Help (for which she was nominated for an Oscar) – has, according to Deadline, been linked to a role in the film for some time now. There have been some scheduling issues given how busy she is, but with a little diary shuffling, she’s now clear to take part if she chooses.

Thanks to Marvel’s usual secrecy surrounding its heroes, there are few details about what she’ll be playing, but it’s said to be a sexy scientist who is Tony Stark (Robert Downey Jr)’s intellectual equal. Will she be a love rival for Gwyneth Paltrow's Pepper Potts? Only time will tell.

Iron Man 3 will be out on May 3, 2013. But Stark will be back a little earlier than that, in some movie about Avengers Assembling. You might have heard of it…