Forget about 'Super Mario Bros.' - Nintendo's most important franchise is one you might not expect

In fact, the highest-selling game franchise from Nintendo — from the Nintendo 3DS to the Nintendo Switch — is "Mario Kart."

It makes a lot of sense: Not only is "Mario Kart" a beloved, long-running franchise, but it collects many of Nintendo's most iconic characters in one place.

Moreover, it's a staple franchise of every Nintendo console owner's library. It's a near-certainty — if you own a Nintendo console, you probably own "Mario Kart."

And every Nintendo console since the Super Nintendo, way back in the mid-'90s, has had a major "Mario Kart" game.

It's the highest-selling game on Nintendo's most recent console, the Switch. As of December 31, 2018, "Mario Kart 8 Deluxe" has sold more than 15 million copies.

"Mario Kart 8 Deluxe" is an update to the Wii U game "Mario Kart 8," as the name indicates. It includes all the downloadable content that came to the Wii U game, some new characters, and a new Battle Mode.

Even though it's a re-release of sorts, it's a loving update to an excellent game that not enough people played on the Wii U. That's no fault of "Mario Kart 8," but is instead due to the fact that so few people bought the Wii U console.

As such, it's found new life on Nintendo's wildly popular Switch console. It probably goes without saying, but if you don't already have "Mario Kart 8 Deluxe" for your Switch, it's absolutely worth the money.

Less than 14 million Wii U consoles were sold, but nearly 9 million people bought "Mario Kart 8."

It is astounding that "Mario Kart 8" sold as many copies as it did on the Wii U, and it's a testament to the franchise that it did.

Few games ever achieve such a high attach rate — the percentage derived from measuring game copies sold against hardware sold. Nearly 75% of Wii U owners bought "Mario Kart 8"!

Even on the Nintendo 3DS, "Mario Kart 7" outsold "Pokémon."

The Nintendo 3DS was Nintendo's last huge hardware hit, with just shy of 75 million units sold.

And yet, even with its portable conceit, "Mario Kart 7" was the highest-selling game. That it still holds the No. 1 spot over any single "Pokémon" game is tremendously impressive.

On Nintendo's last hit home console, the Wii, "Mario Kart Wii" took the No. 2 spot — bested only by a game that was included free with most Wii purchases.

If the Nintendo Wii was known for anything, it was "Wii Sports."

That's because the game was included with the vast majority of Nintendo Wii consoles sold — it came with all Nintendo Wii consoles sold all over the world, except for Japan and South Korea.

As a result, the game has "sold" more than 82 million copies. With the exception of "Wii Sports," the best-selling game on the Nintendo Wii was actually "Mario Kart Wii," with more than 37 million copies sold.

The "Mario Kart" series is an absolute powerhouse that dominates sales across Nintendo consoles, whether we're talking about home consoles with motion controllers or handheld consoles with major "Pokémon" games. And now, with the Nintendo Switch, that dominance continues.