While many talented wrestlers dedicate their entire lives to the craft in hopes of attaining one singular shot at glory, wrestling promotions have never shied away from looking outside the squared circle for athletes who might spur additional ticket sales or ratings.

This is only possible because pro wrestling, unlike just about every other sport on the planet, doesn't require somebody be the absolute best at what they do in order to make the card - the "competition" aspect isn't about actual wins and losses. Guys and gals get to the top of the card through a combination of charisma, raw athleticism, story-telling ability, and general popularity. You'll often hear these packed together as "IT factor," and they're the exact traits that many athletes from non-wrestling backgrounds bring with them as they prepare to pick up in-ring acumen.

Crossover athletes don't always work out. And many wrestlers hate guys who haven't "paid their dues" coming in and taking a spot.

But when promoters like Vince McMahon sense that big time sports people are interested, they'll gladly attempt to turn that interest into a money-making opportunity.

WWE

There's no better example of the crossover athlete than Professional Wrestling's ONLY gold medalist, Kurt Angle. This multi-talented workhorse initially made his name by winning the Olympics - with a broken-freakin'-neck, no less. However, he struggled with post-Olympics life, making such great career choices like this gem of a commercial:

(Can anybody explain to me the match rules of this pizza-toppings wrestling fed?)

Shortly after his 1996 Olympics run, Angle was first offered a 10-year contract with the WWE. However, Angle insisted that he never lose a match - could you imagine a true olympian jobbing to the beer drinkers, crotch-choppers, and gimmick characters of the mid-90's? - and so Vince McMahon not only rescinded the 10 year offer… he just completely ghosted on Angle.

But you know the rest. Angle eventually got hooked on the business, especially the entertainment part (he credits Stone Cold Steve Austin for this), and trained with the legendary Dory Funk Jr. before debuting in late 1998. After that, his legendary athleticism and charisma carried Kurt Angle into an illustrious squared-circle career, and he's often in the "greatest of all time" conversation.

Besides, anybody who can convince WWE fans to non-ironically cheer for a milk trunk probably deserves to be in the Hall of Fame.

The other long-tenured, mid-90's, olympic-calibur crossover star was the feature of a recent WWE Network special.

Known for a stint as Sexual Chocolate (and remembered for one of the strangest segments in pro wrestling history, where an elderly woman literally gave birth to a hand), Mark Henry initially made his name in powerlifting. Just like Angle, Henry did compete in the 1996 Olympic Games, but unlike Angle, injuries prevented him from winning the gold. Fortunately, Henry had already earned the title of "World's Strongest Man" on his path to the Olympics, and that prompted McMahon (who loves superlatives almost as much as he loves superheroes) to offer Henry a rare 10-year deal.

But Henry wasn't initially a star. After huge promotion, his early tenure was marred by injury, and his run as Sexual Chocolate made him more comedian than competitor. In fact, Henry didn't get much main-event love until the mid-2000's. His crowning achievement came in 2011 when Henry conquered Randy Orton to become World Heavyweight Champion.

Henry also is remembered for one of the greatest professional wrestling fake-outs of all time. Wearing a salmon-colored suit, the Hall of Pain creator came down to the ring for what was essentially advertised as a retirement. There, he cried real tears. He gave a heartfelt speech. Henry made the fans forget that just a few months prior his entire gimmick had been ruthlessly beating other superstars senseless. Now, they felt sorrow, not fear.

Until Henry power-slammed John Cena straight to hell. One might even say Cena couldn't see Mark Henry.

And then there's Brock Lesnar. While Lesnar probably shouldn't be considered a "crossover athlete" for his initial run in WWE (yes, he came from an amateur/NCAA background, but if that's the criteria we'd have to lump Jack Swagger, Dolph Ziggler, and a whole bunch of other former freestyle grapplers like… Dean Malenko… on this list), what Brock Lesnar did after leaving WWE in 2004 is nothing short of incredible. He initially played a preseason NFL game for the Minnesota Vikings. (Well, maybe that's not so incredible)

But THEN he trained to become a mixed-martial artist.

Keep in mind this was all AFTER he already had one of the hottest debuts in professional wrestling's history, AFTER he had defeated The Rock to claim his first WWE Championship, and AFTER he had main-evented WrestleMania against Kurt Angle in a classic bout.

And not only did Lesnar go on to compete in MMA - he joined the UFC and took the whole company by storm. He dominated the Heavyweight division before winning the championship, and quickly became a face of the company.

Yet Lesnar still wasn't done. His return to WWE, a RAW after Mania surprise for the ages, opened up a whole new chapter for The Beast. Since then, he's defeated almost every main-eventer, conquered professional wrestling's most illustrious streak, and has held the WWE and Universal Championships in perpetuity.

All this despite not competing on Monday Night RAW - the brand he represents as the reigning, defending champion - in over 15 years.

Lesnar truly is a once-in-a-lifetime superstar.

And if Brock Lesnar laid out the blueprint for crossover success, Ronda Rousey took it to a whole 'nother level. But unlike Lesnar, Rousey did the UFC thing first.

After finding initial success as a women's MMA trailblazer (and really taking over the UFC's top-moneymaker spot that Brock Lesnar had left behind on his return to WWE), Ronda lost two back-to-back fights via knockout. But her spirited trash-talking ability seemed like a perfect fit for professional wrestling.

Rousey debuted right after the first-ever women's Royal Rumble match in one of the biggest crossover moments in WWE history. While she didn't wrestle for a few months (debuting at WrestleMania, no less), her quick title ascension and storyline dominance gave Ronda one of the best rookie years in pro wrestling history.

Not everybody was happy to see Ronda Rousey take over that spot. But, as is playing out in her current feud against Becky Lynch, Rousey's ability to generate interest and money is undeniable.

Of course, not every crossover star has been quite as prosperous.

Real life badass and UFC Hall of Famer Dan Severn found success in the NWA (capturing its top price twice, including a four-year reign). However, his transition to WWE was dead on arrival, and he left after being asked to tattoo "666" on his forehead in an angle where he'd join the Ministry of Darkness. Imagine trying to explain that one to the grandkids.

His real-life rival Ken Shamrock followed a similar path, debuting with WWE in 1997 after time In UFC and quickly catapulting into the main-event scene. Shamrock went on to have mid-card feuds with The Rock, King Mabel, Owen Hart, and Jeff Jarrett. However, Shamrock was phased out in late 1999 after a brief stint as a member of The Union (yes, Mr. Conservative McMahon let a stable with THAT name be the good guys).

One of Shamrock's final feuds was opposite martial arts master and multi-time WWF Hardcore Champion Steve Blackman. While Blackman never reached the MMA heights of Shamrock, he arguably had a more successful WWE run wherein he toppled Shamrock in multiple shoot-style matches before becoming one of the Attitude-era's more memorable comedic characters. His gimmick was, essentially, just being Steve Blackman - an absolute badass with zero personality. So the odd couple pairing of Blackman and the much zanier Al Snow as part of the duo Head Cheese proved to be money.

Heavyweight boxing champion Mike Tyson was brought in to much fanfare, but was really just biding time until his boxing suspension ended. His guest enforcer role at WrestleMania XIV cost Vince & Co $3 million.

Similarly, Knockout specialist Butterbean (Eric Esch) did some work with WWE where he actually boxed instead of wrestled. He's perhaps most remembered for his easy run through the WWF Brawl for All shoot-fight tournament, and having a strange beef with Marc Mero.

WCW

But you can't talk about crossover athletes without mentioning Ted Turner's Wrasslin' Co.

And I don't mean NBA stars Dennis Rodman and Karl Malone switching from hardwood ballers to hardcore wrestlers.

Or ex-Pro Footballer Bill Goldberg, who would become one of WCW's biggest stars ever (despite only know three wrestling moves at the time).

Or that strange NFL on NFL match between Reggie White and Steve McMichael which honest-to-goodness served as Slamboree 1997's co-main event.

I'm talking about the moment in time where head WCW writer and controversy extraordinaire Vince Russo pitched having Ultimate Fighting Championship contender Tank Abbott win the company's biggest prize. The same Tank Abbot who delivered this five-star gem against Sid Vicious

Yep, it's an idea that got Russo fired on the spot.

So here's the rub: crossover stars are a huge part of the business, and can find big success in the major feds - despite the fact that certain purists believe crossover stars inevitably take a spot from an actual "pro wrestler." Yes, they help give the business a boost, and put additional eyes on the product. No, it doesn't always work out.

And listen - if a pro wrestler doesn't like a crossover athlete taking their spot… they can always take their ball, go home, and pursue their own outside interests.