A buzz went through the crowd last week on SmackDown as a man walked purposefully down the new high-tech ramp to the ring to confront newly crowned WWE Champion Brock Lesnar. Paul Heyman's top client has dominated wrestling for years, overpowering foes with his amateur wrestling pedigree and a brutal mean streak.

But, for the first time in forever, Lesnar looked scared.

He'd just beaten the previous champion, Kofi Kingston, in mere seconds. What or who could possibly scare a man like this, a Nordic fighting god who has spent decades tossing grown men around at will?

The answer, of course, was Cain Velasquez.

No mere wrestling rookie, Velasquez is a former UFC heavyweight champion—one who just happens to have dethroned Lesnar in a bout now a decade old. The promotion is hoping a pro wrestling contest between the two men, no strangers to real combat in the cage, will invigorate a struggling product and create the kind of crackling energy only the threat of violence can provide.

And it won't be the first time.

Pro wrestling and mixed martial arts have always been connected at the hip. In Japan, early mixed martial arts bout were staged almost exclusively by wrestlers and their proteges. From Antonio Inoki's historic bout against Muhammad Ali to the founding of Pancrase and PRIDE, wrestlers led the way towards reality combat.

In North America, wrestling roots also ran deep. The Gracie family, founders of the UFC, were trained in grappling by pro wrestler Mitsuyo Maeda and the promotion's early contests had the look and feel of classic territorial wrestling, featuring broad, popular characters like Kimo, David "Tank" Abbott and an assortment of oddities from around the martial arts world whether or not they were the best fighters in the world.

As Velasquez, and both Ronda Rousey and CM Punk before him, the pipeline between the two enterprises is still flowing both ways. Wrestlers want to try their hand at fighting and fighters want to experience the bright lights of big time wrestling. 

What follows is a list of WWE stars who have tried their hand at fighting for real, testing themselves in the unforgiving cage. Some will feel familiar. Others might surprise you. But all were willing to bet on themselves in a honest-to-goodness fight—so never let anyone tell you wrestlers aren't tough as nails.

Bam Bam Bigelow

MMA Record: 0-1

While Ken Shamrock is often credited as the first athlete to build a bridge between WWE and mixed martial arts, that's not quite the truth.

Months before Shamrock kicked off his WWE career as the special referee for Bret Hart's WrestleMania grudge match with "Stone Cold" Steve Austin, former wrestling star Bam Bam Bigelow was making his own ill-fated MMA debut.

Bigelow, a fearsome specimen of a man, an athletic 300-pounder with flames tattooed to his skull, seemed a likely candidate for cage fighting glory. But, just three years after the Gracie family re-introduced the sport to the world, the gulf between trained fighters and your everyday tough guys was already enormous—as Kimo Leopaldo proved in this one-sided drubbing.

The "Polar Bear" Paul Varelans had made the opposite trek in June of 1996, departing the Octagon for a one-off shot at wrestling glory in ECW. But it was Shamrock who truly launched the WWE/UFC connection.

"The World's Most Dangerous Man" Ken Shamrock

MMA Record: 28-17-2

A foundational figure in modern mixed martial arts on two continents, Shamrock was forced out of the UFC when political turmoil threatened the sport's very existence.

Signed to a big money contract by WWE in the early stages of the "Monday Night Wars," Shamrock was a solid contributor during the launch of what we now know as the Attitude Era. 

His feud with the Rock was the first major singles program for a future legend still finding his way. In addition to helping the Brahma Bull find his footing as a heel, Shamrock had important matches with all the top stars of the era, including Shawn Michaels, Bret Hart, Steve Austin, and the Undertaker.

Shamrock, however, couldn't escape MMA's hold. After less than three years with the company, he maneuvered his way out of his WWE contract and found his way back to legitimate competition—this time in the ring for Pride Fighting Championship in Japan.

Tony Halme/Ludvig Borga

MMA Record: 1-4

Shortly after Shamrock's high profile WWE Raw debut in 1997, the first former WWE wrestler quietly tread the opposite path.

Few recognized Tony Halme at UFC 13 and he was never acknowledged on the broadcast as a pro wrestler—but the former "Ludvig Borga" fought Randy Couture in both men's Octagon debut. 

Couture, as would become his trademark, was respectful and to-the-point. Halme, his pro wrestling roots showing, told an interviewer “I’m going to rip his arms and legs out of socket.”

It didn't quite go down that way.

Couture, a former Olympic alternate and NCAA runner-up, made short work of the pro wrestler on his way to a Hall of Fame career in the sport. Halme, who fell victim to a choke in just one minute, never fought another MMA bout— though a dubious boxing career and many battles with the law followed.

A hero in his home country of Finland, he wrote four books, had a gold single and even served in Parliament in his 43 years on this planet.Though he eventually lost his fight with alcohol and drug addiction, his legend will never die. Say what you will about Borga's life and times—but they certainly weren't boring. 

Dan "The Beast" Severn

MMA Record: 101-19-7

Like his archival Shamrock, Severn had a pro wrestling background before ever stepping into the UFC Octagon. He, in fact, entered the cage carrying the historic NWA championship and never actually stopped wrestling, even at the height of his UFC fame. 

While Shamrock was able to adapt to the freewheeling, anything-goes Attitude Era, Severn had a hard time fitting into the contemporary WWE scene. His plain black trunks and soft-spoken demeanor didn't cut it in a time when everyone walked on the razor sharp cutting edge.

Severn was a throwback to a different time and wasn't able to navigate the bold new wrestling world of the 1990s. Even a feud with Shamrock, seemingly a no brainer, fizzled in the face of his anti-charisma, and he was soon once again relegated to the regional scene.

Don Frye, Tank Abbott and the Followers

Shamrock's departure from the floundering UFC opened the floodgates. A steady flow of fighters trickled their way into the pro wrestling world, looking for a new home.  The entire sport of MMA felt like an imminent casualty of political pressure and hypocrisy and there were families to feed. 

While Severn followed him to WWE, Don Frye, Brian Johnston and Josh Barnett eventually found their way to New Japan Pro Wrestling. Frye, in particular, was a gangbusters success, emerging as a main event heel on the Japanese scene.

Meanwhile his former opponent, Tank Abbott, was a high profile bust for WCW, joining the promotion just as things began going off the rails en route to an eventual collapse.

Wrestlers continued to test their mettle in MMA as well, including former WWE wrestler Sean O'Haire and future WWE champion Alberto Del Rio, who competed in Japan under a mask as Dos Caras Jr.  But Shamrock's acrimonious departure from WWE, combined with Severn and Abbott's disastrous failures to launch, temporarily closed the doors between WWE and UFC.

It would take a behemoth of a man to shove them open again. 

Brock "The Beast Incarnate" Lesnar

MMA Record: 5-3 (1)

Brock Lesnar was a natural fit for mixed martial arts. Unworldly fast, impossibly strong and meaner than a rattlesnake, the former NCAA champion seemed born for gladiator style combat. 

Unfortunately, the UFC was at a low point in 2000 When Lesnar dispatched Wes Hand for the NCAA heavyweight championship, years away from a triumphant return to glory on Spike TV. That meant the sport, no matter how well he was suited for it, wasn't a viable option.

Instead, Lesnar allowed the WWE to woo him, beginning an unsteady and combustible relationship that blew up after just a couple of years. Court room and public relations battles followed, but in 2007, Lesnar finally found his way to MMA—seven years of his fighting prime sacrificed at the altar of sports entertainment.

As expected, he was a natural, winning the UFC championship in just his fourth fight and becoming the sport's top box office attraction. He eventually lost a battle to Cain Velasquez—but, more importantly, one too diverticulitis.

No longer the same athlete, he found his way, like so many inevitably do, back home to the WWE ring. There he picked up right where he left off, becoming the most dominant champion of his era, a legitimate presence and anachronism in an enterprise increasingly devoid of old school tough guys. 

Bobby Lashley

MMA Record: 15-2

Lashley once represented President Donald Trump under the brightest lights imaginable—the top match at WrestleMania, rarefied air indeed for a professional wrestler. Then a mere reality star, Trump hand selected Lashley to do battle with Umaga, the chosen representative of WWE boss Vince McMahon. At stake were the two titans' respective hair. 

Lashley, of course, emerged victorious. 

But while Trump went on to bigger things, Lashley would never again reach such lofty heights. A year later, he was gone, eventually reemerging as a modern Dan Severn as he mixed independent wrestling with mixed martial arts adventures on the regional scene.

While Lashley, a former U.S. Army wrestler, compiled a respectable record in the sport, it was against a collection of has beens, never weres and men without so much as a Wikipedia entry to validate their chosen lives.

His highest profile MMA fight, a Showtime bout for Elite XC, was supposed to be a showcase bout for a potential title run. Instead, Lashley ran out of steam and was pounded into a bloody mess by journeyman Chad Griggs.

Now back in WWE, Lashley can reminisce on a respectable career in the cage as he makes out with another man's wife. He may not have been the next Brock Lesnar, as so many speculated he might be, but he was no slouch and never embarrassed himself. 

For a pro wrestling crossover, that's high praise indeed. 

Dave Batista

MMA Record: 1-0

Like many in WWE, Dave Batista fell in love with mixed martial arts, fascinated by a world so similar to his own while also being as different as you could possibly imagine.

That's not unusual.

The Undertaker, for example, was a regular presence at UFC events, infatuated with the sport to the point of mixing legitimate holds into his pro wrestling matches.

Unlike most, however, Batista had the fortitude to test himself and step into the unknown. He was opening himself up to criticism—and he certainly got it. I was, unfortunately, at the front of the line, compelled by the aesthetic differences between the vascular wrestling star and his jiggly opponent. 

In retrospect, my vitriol was unfair. No, Batista wasn't a championship level fighter. But he never claimed to be. He was just a man approaching his middle years, taking one last chance to test himself in legitimate athletics, to step into the fire and feel the burn. 

With that as the standard, how could you consider his MMA foray anything but a success?

Shinsuke Nakamura

MMA Record: 3-1 (1)

New NXT import Yujiro Kushida (6-0-2) incorporates plenty of MMA moves in his vast arsenal—so his prize fighting background isn't much of a surprise. Most WWE fans, however, likely have no idea that the flamboyant, artsy Intercontinental champion Shinsuke Nakamura has an MMA past.

But early in his career, New Japan Pro Wrestling was a very different place.

Founder Antonio Inoki had pushed the promotion towards legitimacy, bringing in MMA stars to lend his wrestlers additional gravitas and putting an emphasis on wrestlers who were willing, and able, to venture into reality combat as well as the wrestling ring.

Nakamura, a former college wrestler, fit that bill. So, despite New Japan's strictly hierarchal system, he was elevated to the very top of the card as a mere rookie, becoming the youngest ever IWGP champion while more than holding his own in MMA competition. 

While long forgotten by most, his short fighting career was integral to his tough guy persona and initial, unprecedented rise to the top of Japan's top wrestling promotion.

Phil "CM Punk" Brooks

MMA Record: 0-2

While NXT has made the transition seem old hat over the last few years, CM Punk broke real ground by becoming the first independent wrestling darling to find success in the corporate world of WWE.

It wasn't always easy.

Punk, famously and publicly, had many disagreements with the WWE brass. And, while he became a major part of the promotion's programming, he could never quite supplant John Cena as WWE's top star.

Eventually the toxic relationship proved too much. Punk left WWE on terrible terms, willing to leave seven-figure behind to pursue a dream few knew he had—athletic glory.

In 2016, he followed his heart right into UFC's Octagon. And, while the results were perhaps not what he hoped, no one can ever deny he had the courage to try.

Shayna Baszler

MMA Record: 15-11

While women like Sonya Deville had come into the WWE ring with some MMA experience, Baszler was the first star to make the leap from mixed martial arts to sports entertainment. A protege of Josh Barnett and catch wrestling legend Billy Robinson, NXT champion Baszler was a women's MMA trailblazer. She fought the best of the best, including the fearsome Cris "Cyborg" Justino, before women were even welcome inside the UFC Octagon as anything but ring card girls.

By the time that changed and Ronda Rousey had led a revolution in combat sports, Baszler was past her athletic prime. But, after a stint on the independent scene and a star turn during the 2017 Mae Young Classic, she's found a new home in NXT, bringing a very distinct style to a women's division in desperate need of her brand of pure bad-assery.  

"Rowdy" Ronda Rousey

MMA Record: 12-2

Because she lost her final two bouts inside the UFC Octagon, it's easy to forget just who the hell Ronda Rousey is. Rousey isn't just one of the most important figures in modern mixed martial arts—she's one of the most influential women in all of contemporary athletics.

Rousey success opened the door for women, not just in UFC, but across combat sports. Without her serving as a proof of concept for women's potential box office power, there would be no WWE "Women's Revolution" and no female fighters in high profile boxing bouts.

Rousey created a new space for women, something I hope isn't forgotten as history is rewritten to suit the powerful. 

She continued trailblazing in her short WWE tenure, main eventing WrestleMania with Becky Lynch and bringing with her an unprecedented level of mainstream media attention. She joined a new crop of NXT graduates to help create a world where women's wrestling features athletic based competition and not just gratuitous eye candy.

It's been a welcome change.