As the UFC’s popularity has continued to grow, so too has the number of famous faces with their eyes on the sport. Here we list five of the biggest stars with a passion for MMA.

Tom Hardy

Not only is Tom Hardy currently starring alongside Leonardo DiCaprio in Oscar-nominated hit The Revenant, but he is also a proud MMA fan! The Englishman is even friends with one of the UK’s hottest young prospects, Jack McGann.

“Fighters are some of the most chilled and kind people I’ve had the pleasure of meeting,” Hardy told Fighters Only. “They can do some of the most unbelievably badass things, but then also have a natter and a chill on the matt about life in general with no ego or agenda. They have an amazing range of characteristics.” The full interview can be found inside the February edition of FO.

As well as being a true fan of the sport, Tom also had his own intense MMA training experience when he prepared for his role as brutal MMA brawler Tommy Riordan in Warrior.

Jeremy Piven

When you watch Jeremy Piven portraying self-made retail tycoon Harry Selfridge in popular TV show Mr. Selfridge, he doesn’t strike you as the kind of man who would spend his leisure time at a live combat sports event. But that’s just how good of an actor Jeremy is.

When attending UFC 167 to watch Georges St Pierre defend his welterweight title against Johny Hendricks, Piven said: “All actors are frustrated athletes, so to be in this atmosphere among these elite athletes is a real treat.”

Piven also had the privilege of introducing UFC legend Chuck Liddell to a mainstream audience when the fighter had a cameo role on his show, Entourage. The actor has even tipped former UFC champs Forrest Griffin and Rashad Evans as men who he believes could be future stars of the acting world.

Charlize Theron

In case you thought all MMA fans were big, loud, hairy men in Affliction t-shirts, stunning Hollywood actress Charlize Theron is here to prove you wrong. And, what’s more, she might be a more passionate fan than any of the men on our list.

“I am absolutely obsessed. Completely, completely and utterly obsessed… I lose my voice, I go that nuts. I get really into it,” Theron explained when she guested on Conan.

“I think it’s such an incredible sport. These guys are incredible athletes… And yet, at the same time, I wonder what it says about me that I like sweaty, hot men bleeding all over each other and bashing each other in the face. But I can live with that.”

Anthony Kiedis

You might not be familiar with the name Anthony Kiedis, but you will almost certainly have heard of the band he fronts, Red Hot Chili Peppers. The band just so happen to be a favorite of UFC president Dana White, and the adoration White has for what Kiedis does appears to be a mutual feeling.

“Honestly, I have about 10,000 UFC memories because I watch it religiously,” said Kiedis. “I love so many fighters. I love Cain (Velasquez), I love (Frankie) Edgar, I even like the fighters I don’t like – I respect all fighters.”

Dave Bautista

It might be questionable including Guardians of the Galaxy star Dave Bautista on our list of celebrity fans as he has actually competed in pro MMA himself, technically making him a fighter as well as a fan. But his flourishing movie career means we simply couldn’t leave him out.

Bautista began training in Brazilian jiu-jitsu under Cesar Gracie – trainer of top UFC fighter Nick Diaz – several years ago. And it was actually Diaz who was Dave’s gateway into training with Gracie.

“Since 2010 I wanted to start picking up jiu-jitsu,” he said. “Cesar Gracie was a very well respected person in the MMA world and, of course, the martial arts world. I really wanted to work with him so I was lucky enough, through a friend, to hook up with Nick Diaz and he invited me to come out to the academy.”

Read a list of eight of the toughest movie characters in history inside the latest edition of FO magazine.