Though we aren’t sure of her role yet, Abigail Spencer (Mad Men, Hawthorne) has apparently joined the cast of director Jon Favreau‘s upcoming film, Cowboys & Aliens which is currently in production. Spencer joins a cast that includes Daniel Craig, Sam Rockwell, Olivia Wilde, Paul Dano, Harrison Ford, Keith Carradine, Clancy Brown, Adam Beach and Walton Goggins.

The casting news came straight from one of the stars of the film, Olivia Wilde (TRON: Legacy) who jumped on twitter to personally welcome Ms. Spencer to the cast. Check out her quote below!

Via @oliviawilde

Abigail Spencer, welcome to the cast of Cowboys & Aliens!!! She is lovely, funny, gorgeous (duh), and talented. this cast ROCKS.

let’s face it, i am spoiled by the outrageous level of talent I am surrounded by on all sets I’m lucky enough to work on. me=lucky

Official Synopsis:

1873. Arizona Territory. A stranger (Craig) with no memory of his past stumbles into the hard desert town of Absolution. The only hint to his history is a mysterious shackle that encircles one wrist. What he discovers is that the people of Absolution don’t welcome strangers, and nobody makes a move on its streets unless ordered to do so by the iron-fisted Colonel Dolarhyde (Ford). It’s a town that lives in fear.

But Absolution is about to experience fear it can scarcely comprehend as the desolate city is attacked by marauders from the sky. Screaming down with breathtaking velocity and blinding lights to abduct the helpless one by one, these monsters challenge everything the residents have ever known.

Now, the stranger they rejected is their only hope for salvation. As this gunslinger slowly starts to remember who he is and where he’s been, he realizes he holds a secret that could give the town a fighting chance against the alien force. With the help of the elusive traveler Ella (Olivia Wilde), he pulls together a posse comprised of former opponents—townsfolk, Dolarhyde and his boys, outlaws and Apache warriors—all in danger of annihilation. United against a common enemy, they will prepare for an epic showdown for survival.

Cowboys & Aliens is slated to hit theaters on July 29th, 2011.