The legend of the 2015 Kansas City Royals came to a full and insane completion here at Citi Field on Sunday night as the team from Missouri did a “Show Me” tap dance on the heads and hearts of every New York Mets fan in the fifth and ultimately final game of the 111th World Series.

The Royals are baseball’s champs for the first time in 30 years, 7-2 in 12 innings. But that number “111” may actually be more appropriate than any final score or time between titles. Apparently, that’s the number of times you have to kill the Royals to keep them dead. Otherwise, it’s just Halloween every day of the postseason until the last soul-scorching defeat they inflict on a merely mortal foe.

The Mets will tell their grandchildren to the end of their days, “Turn off that damn horror movie! No more ‘Night of the Living Dead.’ It seems too real. I had to play the Undead Royals in the World Series!”

Perhaps you need a sense of baseball odds to grasp the near impossibility of a team having eight come-from-behind wins in its 11 road-to-a-title victories, including seven comebacks from two-or-more runs behind. Nah, you get it.

What the Royals did to the team with the superhero nicknames for its stars was right out of a comic book with capitalized captions: Stomp, Crunch, CRASH!!!

The Kansas City Royals celebrate defeating the New York Mets to win the World Series. (Elsa/Getty Images)

That was the sound of two Royals runs in the top of the ninth inning to tie the game, 2-2. Both runs were charged to Matt Harvey, but the blown save should be shared by closer Jeurys Familia and Mets Manager Terry Collins who manned up and said, “It was my fault.”

Whomp, Smash, CLOBBER! That was five-run humiliation in the 12th.

No matter what, it’s the ninth inning that will be remembered as the Royals’ symbol, the moment when, no matter how things seem, they don’t think they have lost.

First, Lorenzo Cain drew a leadoff walk against courageous starter Harvey, who battled through 111 pitches and argued his way back onto the mound — unwisely — in the ninth to try for a complete game.

“He said, ‘I want this game. I want it bad,’ ” said Collins of Harvey, who was pilloried here and around the country when, many weeks ago, he and his agent made noises like they thought his season was going to be ended at 180 innings by mutual agreement out of deference to his recovery from elbow surgery in 2013.

Having come this far, having taken all the risks, and possessing a four-hit shutout going into the ninth, what harm could another 15 or 20 pitches do? Harvey wanted to go all the way. As it was proven, they could cost a lot.

“I let my heart overweigh my gut,” said Collins. “I said, ‘Go get ’em.’ ”

After the leadoff walk, Collins doubled down on “the book” when he should have been using his eyes. “If you’re just going to send him out for one guy, you shouldn’t send him out at all,” said Collins, reciting the managerial mantra.

Eric Hosmer ripped an RBI double into the left field corner and the Royals suddenly had an arm and a leg out of the crypt.

If Collins had trusted Familia with the entire “clean” frame, couldn’t he have held a two-run lead? We’ll never know. Instead, he got his third blown save of this World Series. Yet it was hardly a fair fate.

After Familia got a groundout (with Hosmer moving to third), he also induced a routine grounder to third by the Royals’ Salvador Perez. Then, pure torture, unnecessary suffering by any standard, errupted. Hosmer broke from third base as David Wright threw out Perez at first base. It was a raw, in-your-face, up-three-games-to-one playing-with-house-money gamble. And a crazy (smart) one.

Met first baseman Lucas Duda should have thrown Hosmer out by 10 feet, if not more. Instead, his throw was a complete horrified choke — well wide to the first base side of the plate as Hosmer slid home easily.

“Didn’t work. My fault,” Collins said.

Come on, poor Terry had as much chance once K.C. got rolling as the villagers did against the Frankenstein monster. You let the big dude out, it’s game over.

After that, was there anything left in Queens remaining to be shattered, left strewn on Roosevelt Street for future Mets-fan generations to excavate like the ruins of ancient battles that were fought nobly only to be lost in inept dark comedy?

The final shattering moment arrived in the 12th inning and in absolutely perfect Royals fashion against Mets reliever Addison Reed. Perez poked a leadoff single to right, the opposite field. With the Royals, it always starts with a single.

The Royals keep 17 pinch runners on their bench. Or so it seems. Jarrod Dyson did the duties and, like a good Royal, stole second base with 10 feet to spare. Alex Gordon grounded out, moving Dyson to third. Textbook baseball.

Far at the end of the Royals’ bench sat utility infielder Christian Colon. He had not batted in this postseason. Thanks to a bad umpiring call on a checked swing he was quickly in an 0-2 hole. This is when you know a season is one for the ages — at least the ages in Kansas City. Colon ripped a line drive single to left to tie the game as if the ball had been put on a tee.

Thereafter, Daniel Murphy, goat of Game 4 for an error, booted another grounder and, as will happen, more Royals scored — one on an Alcides Escobar single and the final three on a scorching Cain double up the left field gap.

Where did the Royals’ incredible, seldom-dented confidence come from?

Actually, it dates to one day — Sept. 30, 2014 — and has been building for more than 13 months. That day deserves a return visit since it was exactly the kind of transformative moment that other richer or more supposedly talented teams, like the Los Angeles Dodgers and Washington Nationals have not managed. Often, a talented team needs one seminal game, one defining moment, to believe that it has found its identity. Which comes first, performance or confidence?

In the eighth inning of a wild-card game, Kansas City trailed Oakland and its ace Jon Lester, 7-3. The Royals’ chance of advancing to the Division Series was three percent. It appeared that the Royals would remain what they have been for almost 30 years — an irrelevant team that occasionally has a good year, but never leaves its mark on the sport. Or at least not since its only previous World Series win in ’85.

Then the Royals hit three groundballs. That’s all, just three grounders. Two of them found holes, the third was an out but advanced a runner. K.C. stole a base, then stole another. The A’s got rattled and issued a walk. Finally, a Royal actually hit a line drive — a single. After another stolen base, then a wild pitch, the score was 7-6. Next inning, a single, a sacrifice bunt, a stolen base, a sacrifice fly: 7-7.

While barely bruising the baseball, the Royals were on the verge of a miracle comeback. In the 12th inning, they fell behind again. But they wouldn’t die: A triple, a groundball single, a steal and, finally, another goofy lunging groundball single: Royals 9, A’s 8.

And in that game, who came off the bench to single home the tying run, then steal second, then score the winning run? Some Royals star?

No, it was Christian Colon. Yeah, same guy.

That’s when the legend was born. That’s when the history of the Royals changed. If the Royals had lost to Oakland, would they have spent the money and made the deadline trades of ’15 to get Ben Zobrist and Cueto to help put them so close to the top now? Would their front office, and their own key players, have believed in their odd throw-back low-rent methods?

After all, what kind of team, in ’15, thinks it can beat everybody with humble contact hitting, few walks, less home runs, pinch runners, stolen bases, a deep bullpen and a swift defense designed to compensate for inexpensive starting pitching?

Big league franchises build their teams, concoct their theories on how baseball should be played, over long periods of years. But, often, the whole trajectory of a team’s history can be changed in one game or even one inning. A few plays, a few bounces, changes how a team sees itself.

Someday, the Royals will awaken from this magnificent trance and look at the backs of their baseball cards. They will see a team of very good to just-short-of-wonderful players. But they will not discover a dugout full of future Hall of Famers. They will realize that they are talented mortals.

Don’t tell the Mets. Or their fans. Or anyone who saw this game. For one season, Kansas City epitomized never-say-die and against-all-odds. These were the Draw-To-A-Inside-Straight-Flush Royals. Never bet against them.