Spoilers! Expect ‘Fallout’ from ‘M:I’ ending

Spoiler alert! We’re discussing the thrilling ending of “Mission: Impossible – Fallout.” If you haven’t seen it yet and don’t want to know, STOP READING.

Henry Cavill brings swagger, a fantastic mustache and menace to his brutal CIA agent, August Walker, in “Mission: Impossible – Fallout.” He provides the crucial dark balance to Tom Cruise’s Boy Scout spy-with-a-heart, Ethan Hunt.

We’re really going to miss Walker, who will definitely not be a spicy addition to Hunt’s IMF spy team in the next, inevitable “M:I” movie.

The reasoning is simple. Walker and Hunt’s tension boils over big time – especially when Walker is revealed to be a treacherous mole working with evil Solomon Lane (Sean Harris), intent on bringing an atomic end to world order.

Hunt gets in the way of a planned nuclear explosion. After their dueling helicopters crash, the two battle on a sheer cliff in an unforgettable knockdown ending. This battle royale concludes with Hunt dislodging a cargo hook holding a precariously dangling helicopter – sending the copter to the ground and the hook directly into Walker’s head.

Yeah, we won’t be seeing Walker again after that certain death.

“He earns it,” director Christopher McQuarrie says of the hook-in-head outcome. “There’s a moment in the story where there’s absolutely no coming back for Walker.”

Cruise had reservations about casting Cavill, because he knew audiences would enjoy seeing the two spies butt heads, seemingly from the same team.

“Cruise’s big concern was that he felt like this would turn out to be a buddy movie,” McQuarrie says. “And if the chemistry was such between the two of them, (people) would be disappointed when it turned out, no, this does not end well for these guys.”

Especially Walker. Rest his twisted heart.

The 22-year-old “Mission: Impossible” franchise generally picks up and keeps characters (such as Rebecca Ferguson’s Ilsa or Alec Baldwin’s Hunley) for further installments. So killing off a great character like Walker even hurt McQuarrie.

“We were afraid that audiences would be disappointed when they didn’t turn out to be buddies,” McQuarrie says. “But by the end of the movie, I was the one disappointed. I would’ve loved to have seen Walker live.”

But he believes the death was the right call, because audiences demand the ultimate screen price for Walker’s treachery.

“You have to give them what they want,” McQuarrie says before pausing to think. “But maybe Walker has a twin brother, or a clone.”

That’s a joke, we’re pretty sure. But Cavill, whose day job is playing the earnest Superman in the DC Extended Universe, shows he can embody dark with just a perfect lift of the eyebrow.

“He’s not somebody people imagine being a villain,” says McQuarrie. “Tom asked me, ‘Will people buy it?’ I said, ‘Absolutely.’ He has a great sense of humor. Anybody with that wicked sense of humor can play a villain.”

Cavill portrays a great, physically powerful villain in a franchise whose most memorable antagonist thus far has been Philip Seymour Hoffman’s black market arms dealer Owen Davian in 2006’s “Mission: Impossible III.”

Walker brings the brawn, and a suitably powerful conclusion.

“Henry’s big and imposing and only became more terrifying as the movie went on,” says McQuarrie. “That led people to enjoy the most satisfying conclusion for this villain.”

Cavill rocks the mustache and the mean as Walker – a far cry from his day job as Superman.

IMF’s Ethan Hunt (Tom Cruise) doesn’t always agree with his unwelcome new partner – younger, taller and fitter CIA agent August Walker (Henry Cavill) – in “Mission: Impossible – Fallout.” PHOTOS BY DAVID JAMES/PARAMOUNT