Jessica Biel is joining the cast of The Wolverine, James Mangold's effort to rehabilitate the solo X-Man franchise, as a character called Viper. But originally she had a different name: Madame Hydra.
Created by Jim Steranko, Madame Hydra was a femme fatale character who worked for HYDRA (duh) before splintering off on her own and taking on the new identity Viper. As Viper she was a member of the Serpent Society and she hijacked the SHIELD Helicarrier in an attempt to crash it into Congress.
So what the hell is she doing in The Wolverine? Well, Viper fell in love with the Silver Samurai, a Japanese mutant who will be playing a role in The Wolverine. And she was, at one point, the dictator of the nation of Madripoor, a fictional country where many of Wolverine's comic adventures have taken place.
In the comics Viper is an international terrorist with a major network of operatives. There's no telling how she'll be used in the film - the Fox movies haven't been slaves to accuracy when it comes to this stuff, and the films seem happy to just use the names of characters.
What I find interesting about this is the way it reveals the complicated web of rights to the Marvel characters. I bet that Madame Hydra is available for a Captain America movie, despite being the same 'person' as Viper. Also, her character has battled the ninja clan The Hand, which is made up of Daredevil characters. Fox still has Daredevil - wouldn't it be interesting if they brought The Hand in and began creating their own mini shared universe?