In their time on the big-screen, Professor Charles Xavier and his X-Men have battled their fair share of capable villains, from the charismatic Magneto to the snarling Sabretooth and beyond. But in this coming summer's [article id="1721007"]"X-Men: Days of Future Past,"[/article] the stakes have literally never been higher.

"Days of Future Past," directed by Bryan Singer, combines the casts of the original "X-Men" movie trilogy and 2011's "X-Men: First Class," in a time-travel mash-up that forces Xavier and Magneto's minions to work together against a common foe: the Sentinels -- mutant-hunting, giant-sized androids, and some of the most popular "X-Men" villains from the comics.

The Sentinels have made their official debut today, thanks to Singer and Empire Magazine. Throughout the day, Empire and Singer will unveil 25 different covers featuring new images from "Days of Future Past," beginning with this first look at the Sentinel Mark I.

First up, here's a look at the #Sentinel Mark I, circa 1973. #XMen #Empire25 @EmpireMagazine pic.twitter.com/gNcwwc68FX

— Bryan Singer (@BryanSinger) January 27, 2014

In "Days of Future Past," the Sentinels are created by scientist Bolivar Trask, played by "Game of Thrones" Emmy-winner Peter Dinklage. (Dinklage is also the subject of his own Empire cover.) Trask's construction of the Sentinels dates back to 1973, according to Singer, indicating that the Sentinel Mark I is just one of a few versions of the mutant-killing machines that we'll see in the movie. Indeed, perhaps it's just one of a few different Sentinels we'll see today.

As of this writing, Singer and Empire have also revealed first-looks at returning hero Alex "Havoc" Summers, and returning villains William Stryker and Toad. Actor Evan Jonigkeit plays the latter villain, taking over from Ray Park, who originated the role of Toad in the first "X-Men" film.

"It's a generation story of how he came to be," [article id="1720001"]Jonigkeit told MTV News[/article] earlier in the month of his work as Toad. "It's darker. I would say it's a darker tone."

"X-Men: Days of Future Past" hits theaters on May 23.

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