LAS VEGAS -- The UFC Hall of Fame gained four new inductees on Saturday. Seminal figures B.J. Penn, Bas Rutten, and Jeff Blatnick, along with the classic 2005 fight between Matt Hughes and Frank Trigg, were honored at a lively ceremony in front of a packed house at the UFC Fan Expo. The quartet entered the Hall of Fame in the Modern Era wing, the Pioneer wing, the Contributor wing, and the Fight wing, respectively.

The highlight of the day was Penn (16-10-2), a beloved figure who remains the most decorated and dominant UFC lightweight champion of all-time, and one of the only two-division champions in UFC history alongside Randy Couture. Penn's ascent up the sport was the stuff of legends. Despite having no prior experience in MMA, he debuted in 2001 as a 22-year-old destructive force, racking up a trio of first-round knockouts and validating the moniker with which he became synonymous, "The Prodigy."

"All I wanted to do was become the lightweight champion, beat Jens Pulver, and retire," an emotional Penn said. "I always knew the UFC would get this big. But I'm a small town guy, so I just wanted to become the champion, prove to myself that I could do it, go back to a normal life, and if anybody ever talked to me about the UFC, I could say, ‘hey yeah, I know about that. I used to be the champ once. Here's my belt.' That was my whole dream."

It was Penn's total disregard for weight divisions that became his true calling card. Over the course of his career, the 5-foot-9 Hawaiian fought everywhere and anywhere, competing from 155 pounds all the way to an openweight contest against future UFC champion Lyoto Machida.

In 2004, Penn stunned the mixed martial arts world by moving up to welterweight and capturing the UFC welterweight strap from then-champion Matt Hughes. Three years later, he returned to his home at lightweight, won the vacant UFC 155-pound title, then set out on a path of destruction in a memorable slew of victories that saw him defend his belt a record three times, all by way of stoppage.

Despite the rough run that ended his career, Penn is widely considered to be the greatest lightweight to ever compete in mixed martial arts.

"Fans ask me all the time, ‘B.J., do you think you did enough with the time that you had?'" Penn said. "To them I answer, no I didn't do enough. I did way too much, more than I ever wanted to do."

Rutten (28-4-1) is a former UFC heavyweight champion, having won the title with a split decision over Kevin Randleman in 1999, although it's his accomplishments outside of the UFC that he'll be most remembered for. In the early days of the sport, the Netherland native was one of the most devastating forces in the heavyweight division, racking up a remarkable 22-fight unbeaten streak from 1995 to 2006, a majority of which was fought under the Pancrase banner, and all but one of which was ended inside of the first round.

Rutten most notably beat Frank Shamrock twice during his run. An infamous proponent of the liver shot, "El Guapo" captured the King of Pancrase title with a guillotine choke over Minoru Suzuki in 1995, then never relinquished the mantle until his retirement due to injuries in 1999. That would not be the end though, as Rutten reemerged in 2006 to compete one last time, defeating Ruben Villareal via leg kicks in less that four minutes before departing back to the broadcast booth, where he remains to this day.

"When fighters ask me, ‘what is your greatest motivation for becoming a fighter?' I always say the same line," Rutten said. "Henry IV came up with it, and it applies to anything, any person, any job. Just ask yourself, how do you want to be remembered when die? That's it. And when you really think about that line, that should be all the motivation for you. Trust me, I made a lot of mistakes, but it is what you do with those mistakes that makes you who you are. So how am I going to be remembered?

"Just a decent guy. And a guy who can kick ass and has some crazy barfight stories."

Though he never competed, Blatnick stands today as one of the most influential and instrumental figures in helping the sport climb out of its dark era. An Olympic gold medalist, Blatnick first joined the UFC as an announcer in 1994. He was raised to the position of UFC commissioner four years later, and he immediately set out to make his mark, helping establish the rule book and judging criteria that would ultimately gain the sport sanctioning from state commissions.

He also coined the phrase "mixed martial arts," ushering a shift away from the notoriety associated with the sport's previous name, "No Holds Barred." Blatnick passed away in 2012 at the age of 55, having seen the sport he helped mold rise to heights that once seemed impossible.

"Even though Jeff would've never said it, I know that he would've been very proud today," said Blatnick's wife, Lori Blatnick, who accepted the award in his honor.

"I miss him terribly, and I thank any and all involved in granting him this deserved award," said Blatick's longtime friend, New Jersey commissioner Nick Lembo.. "From the bottom of my hearts, from his friends and family, thank you all."

Rounding out the class of 2015 was the classic rematch between then-UFC welterweight champion Matt Hughes and challenger Frank Trigg. The two veterans first met in 2003, with Hughes winning the heated fight with a first-round submission. Though the bout was memorable, it was nothing compared to their second meeting two years later.

In an unbelievable sequence, Hughes recovered from a harrowing beating that began with an unchecked low blow, broke free from a rear-naked choke, hoisted Trigg high into the air, sprinted across the cage then slammed him hard onto the mat. Trigg could never recover, ultimately succumbing to a rear-naked choke at 3:54 of the opening round.

"It was the most epic battle that I have ever been a part of," Trigg said.