The “Iron Man 2” cast is already jam-packed with fresh actors from Don Cheadle and Scarlett Johansson to Mickey Rourke and Sam Rockwell. If you’re concerned about how director Jon Favreau will handle such a sizable ensemble, let’s add some more worries to your plate — two more actors have joined Tony Stark’s second adventure.
According to The Hollywood Reporter, Kate Mara and Clark Gregg have joined the cast of “Iron Man 2.” Gregg reprises his role as Agent Phil Coulson, the S.H.I.E.L.D. agent that repeatedly nudged Pepper Potts for information on her employer in “Iron Man.”

Mara’s part in the Marvel superhero flick is currently being kept under wraps. The actress is perhaps best known for her role as Heath Ledger’s daughter in “Brokeback Mountain,” though she also played a computer expert in the fifth season of “24.”

Given the secrecy of Mara’s role, it’s entirely likely that she’s playing an important role in the Marvel mythology currently being laid out on film. Whether that means she has a significant part in this movie or an overarching cameo a la Samuel L. Jackson as Nick Fury in “Iron Man” remains up in the air.

The possibilities of who Mara could play seem limitless given the pantheon of female characters in the Marvel Universe. Maybe she’ll star as Janet Van Dyne, better known as the super-tiny superhero Wasp. As Marvel begins gearing up for “The Avengers,” it might make sense to use “Iron Man 2″ as a platform to introduce the relatively unfamiliar Wasp to moviegoers.

Then again, as she was announced alongside Gregg’s S.H.I.E.L.D. agent, perhaps Mara will portray Sharon Carter, a fellow government operative and love interest for Steve Rogers, allowing the character to reappear in “The First Avenger: Captain America.”

We could speculate all day, but we’re certain to learn Mara’s role when “Iron Man 2″ hits theaters on May 7, 2010 — unless Jon Favreau spills the beans on Twitter first!

What do you think of the casting of Kate Mara? Who do you think she’ll play? Are you psyched for Clark Gregg’s return? Give us your thoughts in the comments!