Once upon a time, the WWE's top stars usually fit into a cookie cutter mold.
Either a star had some sort of over-the-top, larger-than-life personality, a bodybuilder physique or some combination of both.
By and large, you could simply look at a guy and tell whether or not he was ever going to be a world champion or even a main eventer.
Every now and then, however, someone came a long and broke that mold.
Whether it was because of his size, his look or his in-ring abilities, that superstar turned the WWE on its head by reaching the promised land and becoming one of the company's top stars.
Here are seven superstars who "broke the mold."
Throughout his career, Eddie Guerrero was always an incredibly charismatic performer who excelled in the ring.
However, he stood just 5'8", and for a big chunk of his career was considered a cruiserweight by WWE standards.
That's why Guerrero shocked the world twice in 2004 when he defeated Brock Lesnar at No Way Out to win his first ever WWE championship and successfully defended it against Kurt Angle at WrestleMania XX.
In a controversial interview with Thomas Golianopoulos of Grantland.com, Kevin Nash recently stated that Guerrero's win at WrestleMania helped to essentially kill the business because he was nothing more than a "vanilla midget."
However, what Guerrero's win really did was show that size didn't matter and that a WWE superstar could reach the pinnacle of pro wrestling because of his abilities as both a performer and wrestler.
At that point, Guerrero was the shortest world champion the WWE had seen in years. As we would soon find out, that helped immediately open the door for other "vanilla midgets" to become world champion.
Two months after Eddie Guerrero won the WWE title, another one of those "vanilla midgets" also became world champion.
Chris Benoit, who had won the 2004 Royal Rumble only a few months earlier, went on to face Triple H and Shawn Michaels for the world heavyweight championship at WrestleMania XX in a bout that many consider the best triple threat match of all time.
In the end, it was Benoit who emerged victorious to win the first world title of his career. His triumph set up a huge in-ring celebration along with WWE champion Eddie Guerrero, who had won that title only two months beforehand.
This is the moment that Kevin Nash said killed the business, but in reality, it probably opened up doors that would have remained closed otherwise.
Neither Guerrero nor Benoit stood 6'6", and Benoit was never known for being a great mic worker or the most entertaining character we've ever seen.
Nevertheless, Benoit's abilities as a wrestler trumped all, and he became the world heavyweight champion because of it.
In December 1998, Mankind (a.k.a. Mick Foley) won the WWE championship for the first time.
The three WWE champions before him were "Stone Cold" Steve Austin, Kane and The Rock.
Looking at those three superstars, you picture three jacked-up guys who all fit the description of what your standard pro wrestler looks like.
Needless to say, Mankind didn't exactly fit that mold.
He didn't have the bodybuilder physique or the face of a male model. Heck, he wore a leather mask, a T-shirt that looked like it had never been washed before and a sock on his hand that he called "Mr. Socko."
Yet, those things didn't limit Mankind. Rather, they are what made him thrive.
Mankind was a drastic change from the previous world champions who came before him and many of the ones who followed.
Even to this day, he remains perhaps the most untraditional-looking WWE champion of all time, a true testament to his abilities as a performer and his popularity with the fans.
CM Punk broke down barriers.
Before he won the world heavyweight championship in 2008, that title scene was dominated by guys who dwarfed him in size in Triple H, The Undertaker, Batista, Edge and others.
Punk is not the smallest WWE superstar we've ever seen, but he got so over in 2008 that he left the WWE with almost no choice but to put the title on him.
He continued doing that even afterward, going on to win the world heavyweight title again in 2009 and solidifying himself as a major star in 2011, when his abilities as both a wrestler and performer turned him into the hottest act of the year.
Not only did Punk "break the mold" because of size and his look (he's neither tall nor jacked up), but he also did so by becoming arguably the most successful WWE star who made a name for himself on the indies before joining the WWE.
Though it was Punk's time in the WWE that made him become the second biggest star in the industry, it was his time in Ring of Honor that got him there and helped get him such a huge WWE fanbase so quickly.
It's not a stretch to say that Punk is the biggest indy-to-WWE success story ever or that he paved the way for more indy (and ROH) phenoms—like Daniel Bryan, Antonio Cesaro, Seth Rollins and Dean Ambrose—to make it to the WWE.
When Daniel Bryan signed with the WWE in 2010, the chatter was that he was a phenomenal wrestler, but that he'd probably fail in the WWE because of his size and supposed lack of charisma.
Has he proven everyone wrong or what?
We're only about two and a half years into Bryan's WWE career, and he's already accomplished quite a bit and is currently the hottest act in all of pro wrestling.
Bryan won Money in the Bank in 2011, became the world heavyweight champion last December and then spent all of 2012 defying the odds and becoming the WWE's breakout star.
He has absolutely blown everyone away with his mic work, his charisma, his comedic ability and his in-ring performances. While just about everyone expected the latter, no one could have imagined Bryan having this much success in the WWE, much less doing it this quickly.
If nothing else, Bryan has proved that you don't have to be a tall bodybuilder or be created by the WWE machine to become a major star.
Bryan stands just 5'10" (which is a pretty generous billed height) and became an indy superstar prior to joining the WWE, which are two ingredients that should have made it very hard for him to succeed in the company.
However, that's exactly what Bryan has done on his way to becoming arguably the top overall talent in the world.
On July 23, 2006, King Booker defeated Rey Mysterio at The Great American Bash to win the world heavyweight championship.
Why is this date so important?
It marks the first time that an African American superstar won a world title in the WWE.
Of course, we all recognize Ron Simmons as the first black world champion, but Booker T was the first to win one in the WWE. This is what makes his victory at The Great American Bash such a historic accomplishment.
Before Booker T, no African American star had ever been WWE or world heavyweight champion, but Booker's monumental win opened the door for that to change.
Five years after Booker won the world heavyweight title, Mark Henry did the same thing.
Coincidence? It's possible.
However, had Booker T not beaten Mysterio six years ago, there's really no way to know if Mark Henry or any other African American superstar would have won the world title by now.
Rey Mysterio isn't the first small man to ever win a world title in the WWE.
However, even to this day, he remains the smallest world champion in WWE history.
In many ways, he continued what Eddie Guerrero and Chris Benoit started.
Two years after Guerrero and Benoit won their first world titles, Mysterio won his.
Yes—all 5'6," 165 pounds of him.
Mysterio defeated Randy Orton and Kurt Angle in a triple threat match at WrestleMania 22 in 2006 to become the world heavyweight champion, his first of three world title reigns in the WWE.
It's easy to see how Mysterio broke the mold.
In a giants' world like pro wrestling, his small stature all but ensured that he'd remain a midcarder or tag team competitor for his entire career. However, he defied the odds and became so popular that the WWE decided to reward his tremendous talents with a world title victory.
A lot of fans say that "Mysterio only won the world title because of Eddie's death," but that's a slap in the face to Mysterio.
He won it because he's arguably the best little man of all time.
Drake Oz is a WWE Featured Columnist for Bleacher Report. Follow him on Twitter!