Korean actress Kim Soo-hyun joins 'The Avengers: Age of Ultron' in unknown role

The roster for Joss Whedon's The Avengers: Age of Ultron is already quite extensive, as Quicksilver (Aaron Taylor-Johnson) and Scarlet Witch (Elizabeth Olsen) have joined the cast of characters from the first film. Ultron (James Spader) and Baron von Strucker (Thomas Kretschmann) will serve as antagonists for the film.

But Korean actress Kim Soo-hyun , who also goes by the name Claudia Kim, posted on Twitter earlier this week that she would also play a part in a Marvel movie (translation via Comic Book Movie):

"After a long wait, I'm happy to be back with great news. I have a lot to do ahead of me, but for now, the words 'Welcome to the Marvel Universe' are amazing and kind of overwhelming. I was a fan of Marvel Comics, and if you really like something, looks like fate can make it happen."

The actress did not confirm in which movie she would participate, but a Marvel official told OSEN (via CBM) that Kim would act in The Avengers: Age of Ultron. Unfortunately, the Marvel source could not reveal the character:

"It would be a spoiler, so we can't tell you which character Kim Soo-hyun will play. Marvel always prohibits telling too much about the story. Her character is already decided and the scene is already written so we cast Kim Soo-hyun, but we can't let you know about her character. We only can say that her character is a substantial supporting role."

"Substantial" indicates more than just a cameo role. Perhaps this will be something similar to Black Widow in Iron Man 2, in which the appearance sets up future installments in the MCU?

What are your guesses? Let us know in the comments below.