It seems now every day, there's at least one more story coming out of Marvel Studios developing film slate. After yesterday's bombshell rumor that Joss Whedon was close to locking in a deal to direct "The Avengers." today the Hollywood Reporter has word that actress Hayley Atwell has been cast as Peggy Carter in the upcoming "The First Avenger: Captain America."

While the story contains to official word from either Marvel or Atwell's representatives, THR did successfully break the news that Chris Evans had been cast as the Joe Johnston-directed film's lead role of Steve Rogers. And the casting of the young British native as the female lead falls right in line with the widely reported news that Marvel was looking at English actresses from Emily Blunt to Keira Knightley for the part.

In the comics, Margaret "Peggy" Carter was introduced as a World War II-era love interest for Captain America in flashback by Stan Lee and Jack Kirby in the 1960's. At the time, the character was part of the back story for Rogers modern girlfriend as Peggy was the older sister of Rogers modern girlfriend S.H.I.E.L.D. Agent 13 Sharon Carter. Since then, the two Carter women have been retconned to be aunt and niece rather than siblings, but the inclusion of Peggy in this first 1940s based film bodes well for Sharon's inclusion in films like "The Avengers" down the line.

Of course, no casting news can be taken as 100% accurate until the studio confirms it, and THR also noted that the widely-reported casting of Hugo Weaving as the villain The Red Skull was not yet a done deal.

UPDATE: Shortly after our story went live, Marvel Studios sent CBR the following release confirming that Atwell had indeed signed on to play Peggy Carter:

Hayley Atwell Confirmed as Peggy Carter in Marvel Studios'

CAPTAIN AMERICA: THE FIRST AVENGER

Marvel Studios announced today that Hayley Atwell has been cast to star as Peggy Carter in the studio's highly anticipated movie CAPTAIN AMERICA: THE FIRST AVENGER opposite Chris Evans. In the early comics, Peggy Carter fell in love with Captain America while they fought together in the war effort. The character will be updated for the feature adaptation. Joe Johnston will direct the film penned by Christopher Markus & Stephen McFeely.

Marvel Studios' Kevin Feige will produce CAPTAIN AMERICA: THE FIRST AVENGER. Alan Fine, Stan Lee, David Maisel and Louis D'Esposito will executive produce. The film will be released in the US on July 22, 2011 and distributed by Paramount Pictures.

CAPTAIN AMERICA: THE FIRST AVENGER will focus on the early days of the Marvel Universe when Steve Rogers volunteers to participate in an experimental program that turns him into the Super Soldier known as Captain America.

Atwell will next be seen in PILLARS OF THE EARTH, the 8-part miniseries premiering July 23 on Starz and the TV series THE PRISONER. Her film credits include THE DUCHESS, BRIDESHEAD REVISITED and CASSANDRA'S DREAM.

In addition to CAPTAIN AMERICA: THE FIRST AVENGER, Marvel Studios will release a slate of films based on the Marvel characters including the highly anticipated sequel, IRON MAN 2, starring Robert Downey Jr. and Gwyneth Paltrow on May 7, 2010, THOR on May 6, 2011, and Marvel Studios' THE AVENGERS on May 4, 2012.

Atwell is represented by CAA and United Agents.

Keep checking CBR for more news on "The First Avenger: Captain America" as it becomes available.