Marvel has released the first trailer for “Avengers: Age of Ultron”, and some super fans can’t stop talking about the mystery woman standing next to Thor in one scene.

The mysterious female doesn’t appear to be Natalie Portman’s “Thor” character Jane Foster or Jamie Alexander’s Lady Sif, but many are speculating it is Marvel newcomer Korean actress Kim Soo-hyun, also known as Claudia Kim.

Screen Rant reported back in March the Marvel production cast Kim in a mystery role.

“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,” Kim wrote on her Twitter back in March.

She appears to be a part of the Avengers team, but Marvel has yet to confirm who her character is in the film.  However, her creative agency dropped a hint as to the importance of her character in the franchise when they released a statement about her casting back in March:

“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.”

“The Avengers: Age of Ultron” will be released to theaters on May 1, 2015.