MMA has clearly come a long way since UFC 1, where absolutely everything was legal with the exception of eye-gouging and fish-hooking. Now, fighting has become a lot more regulated: there is a set of rules that ensure the safety of the fighters, and athletic commissions to supervise the use of performance enhancing drugs. Some may say that the regulations is what allowed the sport to grow so quickly on an international level, as it has become more socially accepted.

However, just as in any other sport, not all athletes follow these regulations. For example, some like to use illegal techniques to give them an edge in the fight, such as shots to the groin or illegal knees. In MMA in particular, these techniques are very difficult to enforce, since they are often deemed ''accidental'', while also causing a lot of damage. It is true that accidents can happen at any time, but some athletes are more notorious than others when it comes to using ''dirty'' techniques.

However, the term ''dirty'' does not only apply to the types of techniques used. PED use can also be considered a dirty move, as it gives the competitor a clear advantage while simultaneously posing a threat to his opponent. This list also contains another notion of the term ''dirty fighter'': athletes who have done immoral or illegal things in their life, causing them to stain their professional image as an MMA fighter. Many of these fighters have been fired from their promotion because of their actions, and others have had some serious problems with the law. Here are top 15 dirtiest fighters in MMA:

15 15. Renato Sobral

At UFC 74, Sobral trapped David Heath in an anaconda choke and when Heath tapped, Sobral did not release the choke. After this incident, he was fined $25,000 and released from the UFC. However, instead of making things right with his opponent, he commented on the situation by saying that "he has to learn respect. He deserved that." Another of Sobral's infamous moments is soccer kicking Brad Kohler even when he was already out cold on the ground.

14 14. Ricco Rodriguez

Rodriguez is the first guy on this list that is not famous for his dirty fight moves (even though he once spit on Ben Rothwell during a fight), but for his dirty life. Known and suspended for his cocaine use (he was the first UFC fighter to be suspended for the drug), Rodriguez once got high and crashed his car. When he noticed that his girlfriend was unconscious, he dragged her into the driver's seat in order for it to look like she was the one driving the car. Every time he tells this story, he always has a little smirk on his face.

13 13. War Machine

War Machine is also on this list not because of his dirty fighting, but because of personal "issues". Earlier this year, War Machine allegedly assaulted his adult film star girlfriend Christy Mack. He absolutely disfigured her face, broke her nose, along with other parts of her body, and sent her to the hospital, fighting for her life. War Machine was charged with 52 counts, including two for attempted murder.

12 12. Jason Miller

Another fighter who made the list not because of his dirty fighting (he has some of that as well, but not as much as the others on this list) but because of his constant trouble with the law. Mayhem was arrested several times for allegedly assaulting a police officer, and once attacked an officer with a ceramic tile. Another guy that has to understand that MMA fighters should fight other MMA fighters, not their wives or police officers.

11 11. Josh Barnett

Josh Barnett doesn't use dirty moves like eye pokes or groin shots, but he is one of the notorious symbols of MMA when it comes to PED use. When his fight with Fedor Emilianenko got cancelled due to Barnett testing positive for PEDs, the whole Affliction promotion nearly went bankrupt. What makes it worse is that Barnett never actually admitted to his PED use. Instead, he found someone to blame each and every time: athletic commissions, opponents, and promotions themselves.

10 10. Keith Hackney

It's hard to place Hackney on this list, because at the time that he was competing, all of the "dirty" techniques he used were then considered perfectly legal. Here is a good example: at UFC 4, Hackney faced off with Joe Son and got trapped in a guillotine. He then decided that the best way for him to escape from the choke was to punch Son repeatedly in the groin until he let go of the choke. Legal? Back then, it was. Dirty? Absolutely. In his defense, Son deserved every single one of those shots: I will explain why later on.

9 9. Jon Jones

Some of Jon Jones' signature moves are clearly illegal, while others are simply controversial. For example, his shoulder cranks on Glover Teixera were legal, but, due to their unorthodox style, were seen by many as a dirty move. Same goes for his signature oblique leg kicks, that can be quite dangerous to his opponents. However, Jones' eye-pokes are clearly illegal, but still remain a top choice in the former champion's arsenal.

8 8. Mike Kyle

So many things with this guy. First of all, there is the alleged chest biting of Wes Sims at UFC 47. Yes, chest biting. Just a few months later, there are the repeated shots to the groin against Justin Eilers. Then, there are the fight-ending eye pokes that got him a professional win against Tsuyoshi Kohsaka. There are also more eye-gouging incidents against several opponents, illegal kicks, punches after the bell...need I go on?

7 7. Cheick Kongo

Just like Jon Jones' eye pokes, Kongo's favorite move is not entirely legal: the kick to the groin. Kongo absolutely LOVES the kick to the groin. In fact, he loves it so much he used it on Travis Browne, Mirko Cro Cop, and many others. The thing with groin shots is that they rarely lead to a point deduction, since they are most of the time considered unintentional. Maybe that's what Kongo was telling himself when he repeatedly kneed Cro Cop in the groin at UFC 75.

6 6. Gerard Gordeau

This is another guy whose dirty techniques were legal in the early UFC events, but should still be placed on this list. When Gordeau fought Yuki Nakai, he gouged his eye so hard that Nakai permanently lost vision from that eye. Despite the eye-gouging, Gordeau still managed to lose the fight. Another good example of Gordeau's infamous moves is his biting of Royce Gracie, a fight that he also lost. Karma? I'd like to think so.

5 5. Joe Son

I talked earlier about how Joe Son deserved every single shot to the groin at UFC 4, courtesy of Keith Hackney. Although Son is not a dirty fighter, he is most certainly a terrible person. In 2011, Son was sentenced to life in prison after he was found guilty of torturing and gang-raping a woman who was walking her dog on Christmas Eve. While in prison Son has also admitted to killing his cellmate. Definitely not a man who belongs in professional MMA, or in civilized society.

4 4. Rob Emerson

Rob Emerson is known for his disrespectful and somewhat violent comments towards MMA judges, but it is not these comments that put him on this list. In 2000, Emerson was arrested for being part of the Lords of South Country, a gang operating in Orange County. However, this "gang" is not your typical biker gang or drug ring. The Lords of South Country is an association of privileged kids who, during their spare time, entertain themselves by assaulting innocent people. Keep it in the cage, Rob.

3 3. Nate Marquardt

Sure this guy seems like a nice guy now, always humble and respectful of his opponents, but how many of you remember his early career? That time when he sucker-punched Rousimar Palhares, that time where illegally kneed Thales Leiles several times, and all of those other unsportsmanlike actions inside of the octagon. On top of that, Marquardt has had numerous problems with PED use, leading to his departure from the UFC in 2011.

2 2. Gilbert Yvel

THREE losses by disqualification. Not one, not two, but THREE. The first was caused when he choked someone to sleep: but instead of choking his opponent, he choked the referee. The second DQ came from repeatedly eye-gouging MMA legend Don Frye. Finally, the third DQ came from, you guessed it, biting. All this is enough to put Yvel on the no.2 spot, but let's not forget his long history of fighting after the bell and eye gouging.

1 1. Rousimar Palhares

Ah, Rousimar Palhares. With an absolutely astonishing technique in Jiu-Jitsu, he could have been an absolute MMA star. Too bad he got fired from almost every promotion he's ever fought in. Palhares is notorious for holding submissions for way too long after his opponent taps, and ever after the referee tries to separate the fight. To make matters worse, Palhares' favorite submission is the heel-hook: a submission that can end the opponent's career if held for too long. And like Josh Barnett, Palhares has never apologized for his behavior inside of the octagon, making him the dirtiest fighter in MMA.