UPDATE: Marvel has just made it official.

Here’s the full press release from them, which includes quotes from showrunner Scott Buck, as well as Marvel TV head, Jeph Loeb:

“I’m very excited to have Jessica as our Colleen Wing,” said Executive

Producer and Showrunner, Scott Buck. “She’s shown us that she can

bring both a sense of quiet strength as well as an engaging

vulnerability to the character.” “Jessica brings both a youthful vitality mixed with a strong sense of

authority crucial to the character,” said Executive Producer/Head of

Marvel Television, Jeph Loeb. “And as anyone who’s seen her in ‘Game

of Thrones’ can attest, she can throw down with the best of them,

making her the perfect Colleen Wing.” In “Marvel’s Iron Fist,” Daniel Rand returns to New York City after

being missing for years. He fights against the criminal element

corrupting New York City with his incredible kung-fu mastery and

ability to summon the awesome power of the fiery Iron Fist. “Marvel’s Iron Fist” is produced by Marvel Television in association

with ABC Studios for Netflix.

They also included the following image in with the announcement.

You can read the original unedited article below.

The announcement of Misty Knight as part of Luke Cage’s solo Netflix outing has continued to prove the format a very viable staging ground for some of Marvel’s best-loved, lower-tier superheroes. Now, fellow Daughter of the Dragon and best mate Colleen Wing prepares to enter the fray in the form of Jessica Henwick. According to Entertainment Weekly, Henwick is the latest to join the growing cast list for Iron Fist, the fourth and final pre-Defenders Netflix show due to be released sometime in 2017.

Jessica Henwick has landed the coveted role of martial arts expert Colleen Wing in the Netflix series. A martial arts expert running her own dojo, Colleen will serve as an invaluable ally to Iron Fist, aka Danny Rand (Finn Jones), as he returns to his life in New York. Henwick is the second person – and second Thrones actor – cast in the upcoming action drama. Jones plays the imprisoned knight Ser Loras Tyrell on the HBO drama.

Time and again Wing has proven herself a faithful ally within Danny Rand’s inner circle, having originated along side him during the bronze age era of Marvel’s comic book history. She’s a catsuited, katana-wielding gymnast, schooled in the way of the Samurai with little mercy to spare. Her inclusion is likely to go down well with fans as well as those seeking stronger female representation within Marvel’s ever-growing pantheon of street level heroes. We look forward to seeing how Henwick approaches the role.

Wing is the first of the additional characters we reported on joining the series a while back alongside the folks over at That Hashtag Show, so we can expect castings for Harold Meachum, Joy Meachum, Ward Meachum, Davos, and Shang-Chi.

Keep yourself informed as to all things Iron Fist here.

Iron Fist will enter production in mid-April for a 2017 release.

Source: Entertainment Weekly.