Twenty-five years into the experiment that promised to determine the most effective martial art, the question is all but expired. Evolution has repeatedly proven that a melding of existing styles and a willingness toward adaptability will continually redefine the potent methods of the moment. It is always shifting, changing, developing; a living art form.

In that quarter-center, the UFC has welcomed thousands of fighters to the cage, all with the intent of rising to the top. A scant few have gotten there, able to call themselves a UFC champion. But an even smaller subset remain the best of the best; the most important fighters ever to step foot into the Octagon. While any list is subjective, in considering the measures necessary for inclusion, we focused on criteria including total body of work, strength of schedule, accomplishments, historical importance, and head-to-head results.

With the UFC celebrating its silver anniversary on Nov. 10, this multi-part series pays tributes to the key names that pushed the promotion’s rise.

For Part 1 featuring Nos. 25-16, click here.

For Part 2 featuring Nos. 15-6, click here.

During his heyday, Anderson Silva was part mixed martial artist, part magician. A lean and wiry middleweight, Silva was a combat wizard with an entertainer’s flair, seemingly capable of ending a fight at his whim.

“The Spider” debuted in the Octagon in the summer of 2006. While already known to the fanatics of the sport, his profile exploded in short order when he styled on Chris Leben, knocking out the iron-chinned brawler in just 49 seconds. That single, electric victory was all the UFC brass needed to see to realize they may have something special on their hands, and immediately elevated Silva into the title picture, matching him up with then-champion Rich Franklin.

At the time, Franklin was considered to be a UFC golden boy, a former high school math teacher who had parlayed his love of the martial arts into a lucrative and successful professional sports career. The fight between them was no contest, Silva rearranging Franklin’s nose after a hail of knees from the clinch.

Over a six-year span, Silva embarked on one of the most legendary streaks in MMA history, winning a UFC record 16 straight times.

Over the ensuing six years, Silva continued one of the most legendary streaks in MMA history, winning a UFC record 16 straight times. His victims included fellow legends Dan Henderson and Vitor Belfort, and former UFC champion Forrest Griffin.

Silva’s fighting legacy is a complex one. On one hand, he authored some incredible moments in the cage; his front kick knockout of Belfort is iconic; his fifth-round, Hail Mary submission against Chael Sonnen remains one of the UFC’s great all-time comebacks; his stoppage of Griffin was electric, exemplifying his ability to enter the matrix. Silva knew how to rise to the biggest of occasions. But on the other hand, his quirky personality came to the surface in unusual ways; there were times when he cruised on his talent, almost dismissively bored of his opponent’s challenge. His fights against Thales Leites, Patrick Cote, and Demian Maia come to mind. Still, time after time, he won.

Silva’s legacy gets more complicated when considering his out-of-the-cage issues, namely two suspensions for performance-enhancing drugs. In the first case, which took place in 2015, Silva had two positive tests in the days leading up to, and then after UFC 183. The Nevada Athletic Commission eventually revealed that he’d tested positive for the steroids Drostanolone and Androstane, as well as anti-anxiety medications Oxazepam and Temazepam. Silva was suspended for one year. In November 2017, he again tested positive, this time for the anabolic agent Methyltestosterone and the diuretic Hydrochlorothiazide. The U.S. Anti-Doping Agency later determined that he had not knowingly taken the substances, instead ingesting them through a contaminated supplement, but he was again suspended for one year.

Silva has only won once in the last six years, yet when taken as a whole, his body of work and his thrilling performances merit a spot among the best to ever do it.

When Demetrious Johnson arrived in the UFC, the division he would one day come to dominant in a way no one had ever dominated a division was not even in existence. That problem seemed to be only a minor inconvenience to Johnson, who though undersized, immediately pulled off victories against two of the most popular and successful bantamweights of the time: Norifumi “KID” Yamamoto and Miguel Torres.

That should have been a sign that something special was in our presence, but few could have foreseen what Johnson would turn into, namely, the longest-reigning UFC champion ever in terms of title defenses.

Johnson’s record streak began in September 2012. After knocking off Ian McCall in a flyweight tournament semifinal, he found himself as an underdog to Joseph Benavidez, but edged out a victory via split decision. While the result generated mild controversy, Johnson quickly consolidated power, defeating John Dodson and John Moraga before emphatically stopping Benavidez in a rematch with a first-round knockout.

With that, he was off. In rapid succession, he defeated Ali Bagautinov, Chris Cariaso, Kyoji Horiguchi, and Dodson once more.

Few could have foreseen what Johnson would turn into: The longest-reigning UFC champion ever in terms of title defenses.

That set up a match with the man that most figured would be his most challenging opponent, Olympic wrestling gold medalist Henry Cejudo.

As Johnson often did when faced with a challenge, he stepped up to it, scoring a surprising first-round TKO.

Johnson’s most celebrated in-cage moment took place in April 2017. Facing Ray Borg, Johnson was clearly winning as the fight neared its final moments. Working from Borg’s back near the fence, Johnson picked him up suplex-style, then transitioned to a fight-ending flying armbar submission as Borg crashed toward the mat. It was an astonishing, unprecedented feat, and serves as a perfect representation of Johnson’s improvisational ability.

At his best, Johnson could win in any facet of the fight game. He had power and speed; he could switch stances; his takedown ability and timing worked in perfect tandem; he boasted endless stamina. Wherever your weakness was, he could exploit it.

Johnson was also a great representative of MMA away from the cage. Quiet yet confident, he exuded class and never put the sport or the organization in a negative light. Those morals and ethics carried over into his career, where Johnson always competed with the utmost integrity to go with his ferocious drive.

For part of his career, Johnson was considered the No. 1 pound-for-pound fighter on Earth, and his 11 successful title defenses is a record that may stand for years to come (by contrast, the champion with the longest current streak is Tyron Woodley, with four defenses).

And although he recently lost his belt in a disputed split decision and engineered a trade to ONE Championship, Johnson departs the UFC with a record of brilliance behind him.

Fast nearing the age of 40, Daniel Cormier has repeatedly reiterated that he intends to retire as he reaches that milestone birthday, a somewhat surprising decision given his current standing as a simultaneous two-division UFC champion.

That two-division champion status alone is enough to merit his inclusion on a list of the best fighters ever to compete in the UFC. The most amazing part of Cormier’s achievements here is that he has done so much in just over five years. Cormier didn’t enter the UFC until April 2013, at which time he was already 34 years old. That’s a late start for an assault on the record books, but Cormier rocketed up the list through incredible activity, particularly for a heavier weight class fighter, competing 13 times in 5.5 years.

Cormier’s rise was spectacular to watch in real time. A longtime amateur wrestler who represented the United States in two Olympic Games, he adapted a versatile style that combined surprisingly powerful striking with his world-class grappling ability. One moment, he might be lifting an opponent in a high-amplitude takedown; another, he could be throwing a jab/high kick combination. That ability to mix things up made him a matchup nightmare.

The most amazing part of Cormier’s achievements here is that he has done so much in just over five years.

From the beginning, Cormier fought the best of the division — and sometimes, some of the best of all-time. His wins include all-time greats like Anderson Silva and Dan Henderson, former heavyweight champions including Stipe Miocic and Frank Mir, and longtime top contenders like Alexander Gustafsson and Anthony Johnson.

For a time, the knock on Cormier was that he did not beat Jon Jones. When the two met at UFC 182 in January 2015 for the UFC light heavyweight championship, Jones handed Cormier his first career loss, outpointing him in a unanimous decision. Jones, however, was soon stripped of the belt for an out-of-the-cage hit-and-run incident, and Cormier stepped in, stopping Johnson with a rear-naked choke. The two rematched in 2017, with Jones winning via knockout. But that win was soon overturned after Jones tested positive for the anabolic steroid Turinabol.

But Cormier finally escaped from Jones’ long shadow in July 2018, when he returned to heavyweight to face Miocic in a champion vs. champion bout. Against the odds, Cormier knocked out Miocic in less than a round, becoming a two-division champ.

Still the holder of both the light-heavyweight and heavyweight belts, Cormier has plans to add at least one more chapter to his brilliant history.

2. Jon Jones

When it comes to pure talent, Jon Jones is MMA’s Mozart, its young and inimitable genius, beaming with both natural brilliance and the ability to perform both practiced and improvised feats with aplomb. The MMA world has never seen anything like him, a fighter who made it to the sports’ major league with little more than 18 months of training under his belt, only to surpass any of the lofty expectations set for him.

Athletically, it has always seemed like there was nothing that Jones could not do. Six-foot-four and with an albatross-like wingspan of 84.5 inches, Jones maximized his physical gifts by crafting a style that emphasized his reach and distance control. Opponents would try to breach the space between them, only to be hit from areas where they could not possibly reach him. And then on the rare occasions when they somehow managed to work their way inside, they might either be welcomed by an unforgiving clinch or a Jones’ takedown into his dominant top control.

Jones quickly proved the prodigy label correct, easily besting Stephen Bonnar in just his second trip to the Octagon. A few fights later, his stunning and violent TKO victory over Brandon Vera reinforced his championship potential. Within three more fights, he was fighting for the light heavyweight title. Paired off with Mauricio “Shogun” Rua on short notice, Jones executed one of the most flawless championship performances in major MMA, decimating Rua en route to a third-round TKO.

In the end, Jones’ legacy is complicated. He’s so good that we marvel at what he’s done while simultaneously wondering what could have been.

Suddenly a coronated king, Jones quickly proved unstoppable, scoring consecutive title defense wins against four straight ex-UFC champions: Quinton Jackson, Lyoto Machida, Rashad Evans, and Vitor Belfort, a feat never accomplished before or since.

At UFC 165 in September 2013, Jones faced perhaps his only career moment of in-cage adversity. Trailing two rounds to one against Alexander Gustafsson heading into the championship rounds of their bout, and struggling his way through the fourth, Jones uncorked a brilliant spinning back elbow that rocked Gustafsson. With that, Jones seized momentum and captured each of the final two rounds to escape with the belt. He also defeated his longtime rival Daniel Cormier.

Jones’ legacy as a fighter is not in question; however, he has faced two suspensions for performance-enhancing drugs, one in 2016 and one in 2017. In the first, an arbitration panel concluded that while Jones “is not a drug cheat,” his degree of fault for the test failure was nonetheless “at the very top end of the scale” for a failure to do due diligence on the contaminated pill he took. In the second, a panel found “some degree of fault” for Jones, although it concluded “the violation was not intended nor could it have enhanced” his performance.

These suspensions and other out-of-the-cage problems have cost Jones time, money, and fights; in the last five years, he’s only competed four times.

In the end, his legacy is complicated. He’s so good that we marvel at what he’s done while simultaneously wondering what could have been.

Mixed martial arts is supposed to be a counterculture pursuit, a sport that loves anti-heroes, that prizes the eccentrics and encourages improvisation. How then does it happen that the best fighter ever to set foot in the best organization turns out to be a clean-cut, predictable, polite Canadian? And that the fight world would fall in love with him?

Perhaps he was so off-brand that he was on-brand.

St-Pierre’s career can be broken down into two eras: Before and after Matt Serra. He was quite successful in both periods, but the experience of losing to Serra at UFC 69 in April 2007 proved to be a seminal moment for his development. Prior to it, St-Pierre had been a dynamic and aggressive youngster who chased finishes, sometimes overextending himself in the process. When Serra shocked him, St-Pierre transformed himself, prizing game-planning, strategy and careful execution above highlight reels. In some ways, he added a level of professionalism to the sport that had not previously existed. Surrounding himself with an all-star crew of coaches, St-Pierre obsessed over the small details that are often differentiators in the segue from good to great, and great to G.O.A.T.

It was not enough for him to be a functional wrestler; he wanted to be the best. He wanted to be the fastest scrambler, to boast the best reaction time, to drill every possible scenario to the point where he would recognize it before it developed. Even after winning, St-Pierre would often immediately head back to the locker room and review any perceived mistake he made, however small.

If St-Pierre returns, anything he accomplishes will be pure gravy. His legacy is complete, his greatness is sealed.

His attention to detail was as legendary as his success. St-Pierre dominated the welterweight division for almost six years straight, successfully defending the belt during his second reign nine straight times, a streak that was only broken when he decided to step away from MMA in 2013.

St-Pierre has one of the best winning percentages in UFC history, winning 20 of 22 fights. In addition, he avenged both of his losses in spectacular style. In the first, he stopped Matt Hughes on a head kick and punches to win his first UFC welterweight title; in the second, he walloped Serra in a one-round rout. In addition to that, he holds UFC wins over B.J. Penn (twice), Jake Shields, Carlos Condit, and Nick Diaz.

If St-Pierre had quit for good after beating Johny Hendricks at UFC 167, he might have already done enough for the top spot on the all-time list, but for good measure, he returned after a four-year absence in an attempt to capture a championship in a second weight class. He did so in style, submitting Michael Bisping at UFC 217 in November 2017.

To date, St-Pierre has yet to fight again, yet occasionally, there are rumblings that he would come back to challenge for a third belt. A pairing with Khabib Nurmagomedov has also been rumored.

If St-Pierre returns, anything he accomplishes will be pure gravy. His legacy is complete, his greatness is sealed, and at the quarter-century mark of the UFC, he is the best the organization has ever seen.