Director Pics: Behind-the-Scenes of 'X-Men'

A still from X-Men: Days Of Future Past has been released to celebrate the end of principal photography on the upcoming mutant saga, featuring Hugh Jackman (as Wolverine), James McAvoy (as Charles Xavier) and Nicholas Hoult (as Beast) sporting their finest '70s duds.

From Hugh Jackman's arrival on set as Wolverine to a first look at Jennifer Lawrence back in her blue body paint as Mystique, click the pics for a behind-the-scenes look at the action-packed flick, set to hit theaters May 23, 2014.

"Here's to the next 50 years." That's the August 1 caption X-Men: Days of Future Past director Bryan Singer wrote on his Twitter below this shot of him standing next to a life-sized Sentinel robot. In the movie, which unites the characters from the original X-Men trilogy with their younger selves from X-Men: First Class to fight the ultimate battle, the line of destructive machines are produced by Trask Industries for the sole purpose of destroying mutants.

Bryan Singer confirmed some X-Men: Days of Future Past casting news via Twitter on July 15, 2013. Posting a pic of Lucas Till, who played Alex Summers / Havok in the 2011 film X-Men: First Class, dressed in military garbs, the director tweeted: "Mankind must put an end to war before war puts an end to mankind." -JFK @lucastill #xmen #DaysOfFuturePast"

On June 5, Singer revealed a shot of Michael Fassbender "levitating" as Magneto. The director captioned the pic, writing: "The Dark Knight Rises."

On May 20, 2013, Singer revealed a first look at Jennifer Lawrence doused in blue body paint for her shape-shifting character "Raven Darkhölme/Mystique."

Singer tweeted a pic of Hugh Jackman's back on April 30, 2013, writing: "Fitting @RealHughJackman."

Halle Berry will return as Ororo Munroe, aka Storm. Singer tweeted on April 22, 2013: "Storm Watch."

Shawn Ashmore got into his character as Bobby Drake/Iceman on April 16, 2013. The director tweeted: "Tracking @ShawnRAshmore #XMen #DaysOfFuturePast."

Singer tweeted on May 7, 2013: "Shooting native 3D and Simul-cam. Looks like friggin mission control."

Ellen Page, who plays Kitty Pryde/Shadowcat, gets some direction for her character. Singer wrote on May 3, 2013: "Hello, Kitty @EllenPage #XMen #DaysofFuturePast."

Actor James McAvoy was snapped on May 9, 2013 in a motorized wheelchair taking on the character of Charles Xavier. Singer hashtagged this pic with "#Serpico."