British Actors Patrick Stewart, James McAvoy, Ian McKellen and Irish-German Actor Michael Fassbender
British actors Patrick Stewart (L-R), James McAvoy, Ian McKellen and Irish-German actor Michael Fassbender arrive for the British premiere of 'X-Men: Days of Future Past' at Leicester Square in London in this May 12, 2014 file photo. Reuters

The immortal Apocalypse will make its appearance in the coming "X-Men" sequel, "X-Men: Apocalypse." With the aid of the Four Horsemen and the Clan Akkaba, he is going to be one super-villain who's going to cause big trouble for Marvel's mutant superheroes.

So how big of a super-villain is Apocalypse going to be?

First off, Bryan Singer teased fans with a snapshot of the first page of the movie's script on his Instagram account. Although it didn't reveal much, it is enough to know that Apocalypse, according to Inquisitr, will be "wrecking shop" at the first scene of "X-Men: Apocalypse," as evident on the word "sprawling battle" revealed on the snapshot.

Other words that can be picked out from the snippet are "coil with smoke," "The Nile is streaked with" and most importantly "The Four Horsemen."

Marvel Comics fans are familiar with The Four Horsemen. They are the heralds of the Apocalypse.

So just who is Apocalypse and why should the mutants fear him?

According to ComicBook, Apocalypse is considered the first mutant in the Marvel universe cannon. Thus, he is called En Sabah Nur or "The First One." Born in the city of Akkaba, he was abandoned and left to die in the desert because of his strange grey skin. However, he was rescued by a nomadic tribe called the Sandstormers, who gave him his name. It was with this tribe that he learned his mantra in life, the philosophy of "survival of the fittest."

Over the course of his adult life, his mutant powers manifested. He used it to overthrow Ozymandias who had enslaved his tribe and forced them into labour.

Fast forward to the modern era, the arrival of his travelling nemesis, Cable, forces Apocalypse to recruit his Four Horsemen, led by the Archangel of Death.

Apocalypse does not only have the Four Horsemen but also the Clan Akkaba on his side.

Clan Akkaba is a cult that formed around Apocalypse back in Egypt. They have guarded Apocalypse's legacy ever since, serving as his protector as he hibernates and waking him up in times of need.

Apocalypse does not die. Yes, he is immortal. Thanks to his discovery of Kang the Conqueror's (Rama-Tut) technology, he learned how to regenerate his body so he'd live for centuries. He also meets the Celestials, who granted him his power armour and named him protector of earth's evolution.

Apocalypse is known to be very powerful. He even turned some "X-Men" members onto his side, like Wolverine. The leader of The Four Horsemen was also once the mutant Angel. After receiving a new pair of wings from Apocalypse, Angel became the Archangel of Death. Even Cyclops fell under his power.

The full extent of Apocalypse's power "remains to be seen," according to Marvel's encyclopedia. In the comics, he is seen controlling his own body on a molecular level. In the process, he alters his density and mimicks metals and armours. He can also teleport, grow in size, fly and shape shift. He is believed to be even stronger than The Hulk.

"He came with a clear-cut agenda: 'survival of the fittest.' He didn't care if you were a mutant—if you were weak, you would be destroyed," Marvel editor Bob Harras told Comic Book Resources back in 2009.

"Now, we had given mutants something new to fear: a character who would judge them on their genetic worthiness," Harras added.

All these say how much the "X-Men" will definitely have a hard time battling Apocalypse in the summer of 2016, when "X-Men: Apocalypse" hits the big screen. The Inquisitor concludes that if Bryan Singer and crew would be able to successfully bring out the fearsome, immortal mutant on the big screen, then fans would see a super-villain for the ages.

(Source:YouTube/WatchMojo.com)