Currently, nine fighters reside in the UFC Hall of Fame, with Tito Ortiz being the latest inductee earlier this year.
The first time the UFC put guys in the Hall of Fame was in 2003, when Royce Gracie and Ken Shamrock were inducted.
The rest of the members of the UFC Hall of Fame are Randy Couture, Mark Coleman, Matt Hughes, Chuck Liddell, Dan Severn and Charles "Mask" Lewis.
Saturday night, BJ Penn fights at UFC on Fox 5 against Rory MacDonald. Penn is a former two division champion, where he won titles at lightweight and welterweight.
Penn has faced all comers who were in their prime. He has faced Georges St-Pierre, Matt Hughes, Jens Pulver and even fought outside his weight class when he battled Lyoto Machida in Japan.
With those accolades, Penn is a sure-fire UFC Hall of Famer.
Which other fighters are locks to join Penn? Let's take a look.
We may not have seen Dan Henderson since his epic fight with Shogun Rua at UFC 139, but that doesn't take away what he has done in his career.
Henderson started his MMA career in 1997. He won the UFC 17 middleweight tournament in 1998.
He ended up going to Pride, where he held the Pride welterweight and middleweight championships at the same time. Those were the equivalent of the middleweight and light heavyweight championships.
Henderson returned to the UFC in 2007 and went 3-2 before going to Strikeforce in 2010.
He ended up going back to light heavyweight, and won the Strikeforce light heavyweight title against Rafael "Feijao" Cavalcante in March 2011.
He left Strikeforce with a bang as he went up to heavyweight and defeated Fedor Emelianenko in July 2011.
You don't see many 19-year-olds coming into MMA and making a splash right out of the box.
But most fighters aren't Vitor Belfort.
Belfort walked right into his first UFC show at UFC 12 in 1997 and spent a total of two minutes in the cage while winning the UFC Heavyweight Tournament.
The man known as "The Phenom" has gone on to win the UFC light heavyweight title, beating Randy Couture. Belfort has also faced the likes of Chuck Liddell, Tito Ortiz and Alistair Overeem.
Those accomplishments guarantee Belfort to be a lock for the Hall of Fame.
A former math teacher in the UFC Hall of Fame? If your name is Rich Franklin, then yes.
Franklin was a former UFC middleweight champion and defeated Nate Quarry and David Loiseau before running into some guy named Anderson Silva.
Franklin never won back the title, but he has went on to fight at light heavyweight and catch-weight fights at 190 and 195 pounds. In those bouts, he faced the likes of Wanderlei Silva, Dan Henderson and Vitor Belfort.
When the UFC has needed someone to step up and take a fight, it could always rely on Rich Franklin.
Griffin to the right
Forrest Griffin has stated on numerous occasions that many fighters are a lot more talented than him.
Though the one thing that separates Griffin from those fighters is his heart.
Griffin's fight with Stephan Bonnar at the first Ultimate Fighter Finale is quite arguably the greatest fight of all time.
People have stated that if it wasn't for this fight, the UFC may not even be in existence.
Griffin went on to defeat Quinton "Rampage" Jackson at UFC 86 to win the light heavyweight championship.
Griffin has gone on to defeat the likes of Shogun Rua and has won two out of three fights against Tito Ortiz.
Jackson to the right
When people think of Quinton "Rampage" Jackson, they think of the chain and of him howling like a werewolf.
Jackson, beyond that, has carved one of the best careers in MMA history.
Jackson is the only man to defeat Chuck Liddell twice, the last time being when he defeated Liddell to win the UFC light heavyweight title at UFC 71.
Rampage went on to unify the Pride and UFC titles when he defeated Dan Henderson at UFC 75.
Jackson then went on to coach The Ultimate Fighter two times, which included the heavyweight season that had the highest ratings in recent memory.
Frank Mir has only had two fights outside the UFC, and those were the first two of his career.
Mir has been in the UFC since UFC 34 in 2001, when he defeated Roberto Traven.
Mir went to win the UFC heavyweight title from Tim Sylvia at UFC 48 in 2004, but a tragic motorcycle accident later that year almost ended his career.
Mir was able to come back, and he defeated Brock Lesnar in Lesnar's UFC debut. Mir went on to win the interim UFC heavyweight title when he defeated Antonio Rodrigo Nogueira at UFC 92.
Then Mir went on to rematch Lesnar in a unification bout at UFC 100, in what was the largest PPV event in UFC history, with a reported 1.6 million buys.
Wanderlei Silva has one of the most ferocious styles in all of mixed martial arts. He only knows one speed, and that's moving straight forward.
Silva made his UFC debut at UFC Brazil in 1998, when he faced Vitor Belfort. Silva fought on and off in the UFC before settling in and fighting for Pride.
The "Axe Murderer" went on to win the Pride Middleweight Championship and has defeated the likes of Rampage Jackson and Ricardo Arona. He also faced guys like Mark Hunt and Mirko Cro Cop in heavyweight bouts.
Silva has battled Dan Henderson, Chuck Liddell and Michael Bisping. For these accomplishments, Silva is a lock for the Hall of Fame.
Jones to the right
A 25-year-old already a lock for the UFC Hall of Fame?
When you have accomplished things that no other fighter has done, then absolutely.
Jon Jones is 17-1, with his lone loss being a disqualification to Matt Hamill, in a fight Jones was clearly winning.
If it wasn't for that blemish, we'd be talking about a guy who is 18-0, holds the UFC light heavyweight title and defeated fighters who will be in the UFC Hall of Fame someday.
Those fighters include Vitor Belfort, Rashad Evans, Rampage Jackson, Lyoto Machida and the man he defeated to win the title from, Shogun Rua.
Jones has a chance to go down as the greatest fighter of all time, and right now, he is on his way.
If it wasn't for Matt Serra at UFC 69, we would be talking about Georges St-Pierre as quite arguably the greatest fighter of all time.
St-Pierre, who is the reigning UFC welterweight champion, has faced the most prominent names in MMA since he entered the UFC in 2004.
He has defeated the likes of Matt Hughes, BJ Penn, Sean Sherk and most recently, Carlos Condit, at UFC 154.
With those accolades, St-Pierre is also one of the most popular athletes in Canada. He has won the Canadian Athlete of the Year award numerous times.
What more can you say about Anderson Silva?
The current pound-for-pound king is quite possibly the greatest of all time. We can stop right there, and put him in the UFC Hall of Fame.
In his second fight in the UFC, Silva defeated Rich Franklin to win the UFC middleweight title.
Silva is 16-0 inside the Octagon, has fought mostly at middleweight and has had three fights at light heavyweight.
Silva has fought the likes of Franklin, Dan Henderson and Chael Sonnen.
For all these accomplishments, Silva is a guaranteed lock to be in the UFC Hall of Fame.