Henry Cavill, who plays Superman in the upcoming "Batman v. Superman: Dawn of Justice" sequel, is once again proving that he's also a superhero off-screen.

The 31-year-old has given the world its first look at Superman's alter-ego Clark Kent in costume as part of a promotion for the U.K.’s Royal Marine 1664 Challenge. While he lacks the iconic glasses and tusseled hair that complete the costume, there's likely a phone booth somewhere that can remedy that.

Cavill became an ambassador for the Royal Marines Charitable Trust Fund in May, helping to both celebrate the group's 350th year anniversary and kick off the 1664 Challenge - an intense physical and mental campaign that will see teams ski, sail, cycle, canoe and run 6656km (circa 4136 miles).

“Royal Marine Commandos believe in what they can do," says Cavill in the video. "They have the courage, determination and will to succeed. They make sacrifices and take risks; regrettably, sometimes they have to pay the price for those risks. In recent years they have experienced a significant increase in serious injuries, wounds or illness through current operations. This has not deterred the men of this proud corps; on the contrary, it has spurred them on to help their injured and wounded comrades.

We should not forget what the Royal Marines have done for the country and the many sacrifices that they have made. Now is the time, in their distinguished 350 year history, for everyone to get behind the Royal Marines; and support this extraordinary challenge and this incredible charity,” he adds.

Watch Cavill's support PSA for the 1664 Challenge below. "Batman v. Superman" is slated for release in May 2016.

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Henry Cavill poses as Clark Kent for charity 'Batman v Superman' photo
First look offers up great exposure for the Royal Marines Charitable Trust Fund.