Pro wrestling is an industry that consumes vast amounts of talent, and WWE has regularly relied on the presence of some of boxing’s biggest names to legitimize itself as a mainstream form of sports entertainment.

Boxing may be a massively different industry now than it was back in the day. You might watch some of those big, grandiose matches between competitors like Conor McGregor and Floyd Mayweather and think it’s all not that different from WWE these days. And you’d be right – but boxing is still one of our most historic, legitimate combat sports.

People have been watching it for centuries, and high-profile boxers would typically have more respect than pro wrestlers back then. That’s because they don’t stage fights and people decidedly inflict pain on each other, rather than it happening by chance due to a mishap in the WWE. There’s a lot of cross-over between the two industries, as athletes always tend to go where the most money is.

Boxers have become wrestlers, wrestlers have become boxers – and some athletes have simply appeared on the brand as a novelty attraction in return for massive paychecks. Here’s just six of the biggest boxers who you may have seen on some top sports picks back in the day who’ve made an appearance in WWE.

MIKE TYSON

Iron Mike is synonymous with boxing, one of the sport’s biggest names to this day – and he made his first appearance in WWE in 1998 at Wrestlemania XIV. Tyson was a guest enforcer (and honorary member of D-Generation X) for the main event match between Shawn Michaels and Stone Cold Steve Austin, who was a rising star at the time.

His fee for this small initial series of appearances is estimated at around three million dollars, but the returns for WWE were astonishing. Not only did Tyson’s appearances help bring a significant amount of mainstream sports media coverage to the company, it also increased the purchases of WrestleMania by almost a quarter of million more than the previous installment.

MUHAMMAD ALI

Another one of the greats, Ali appeared in pro wrestling four years after his last fight as a boxer. He actually served as a guest referee/enforcer during the very first WrestleMania, in a stacked tag-team match between Hulk Hogan/Mr. T and “Rowdy” Roddy Piper/Mr. Wonderful.

His boxing days might have been behind him but that didn’t stop Ali from climbing into the ring at one point and taking a few swings at Roddy Piper. Ali’s presence would attract huge amounts of mainstream attention to what was a very young WWF at the time – much like Mike Tyson did a few years later.

Much of Ali’s boxing persona was actually inspired by pro wrestling. In modern times, that aggressive, charismatic bravado seems normal. Mayweather and McGregor are full of attitude, for example – but that all started with Muhammad Ali, inspired by wrestling promos.

FLOYD MAYWEATHER

Love him or hate him, Mayweather is an undefeated champion and a massive draw to any sports events. The methods in which he’s defended that undefeated record is a subject of some controversy, but the man fills seats wherever he goes.

Mayweather – almost the perfect heel –  fought The Big Show in a match at WrestleMania 24, and – unsurprisingly – retained that undefeated record.

MR. T

These days, Mr. T just kind of exists as a meme. It’s easy to forget as a result that he was a very successful actor back in the day – with a serious competitive boxing background too.

His boxing prowess was what earned him the role of Clubber Lang in Rocky III, and this combination of sport and charisma made him a natural fit for pro wrestling. He would team up with Hulk Hogan for the main event match against Rowdy Roddy Piper and Mr. Wonderful – the very same one refereed by Muhammad Ali.

TYSON FURY

This one’s fresh (at least compared to some of the other entries on this list). Tyson Fury was embroiled in a feud with one of WWE’s (literally) biggest talents, Braun Strowman. It was a slow build over a few episodes of SmackDown – Strowman taunted Fury, who was sitting at the ringside, eventually hurling Dolph Ziggler at him. Fury jumped the rail and went for Strowman.

Later on, Fury would demand an apology that Strowman refused to give, and another brawl broke out. The two went on to have an official confrontation at Crown Jewel in Saudi Arabia. Fury unsurprisingly won the fight, and pocketed a cool fifteen million dollars for his troubles.

Unlike many of the other Boxers though, Tyson Fury is still going strong in the sport. Most recently he fought and beat Deontay Wilder in their third bout. And whilst many were calling for him to fight Anthony Joshua next, you’ll find him on the top sports picks for his next fight, likely to be against Dillian Whyte instead who is -200 to be his next opponent. The Gypsy King will be favorite for the fight, should it go ahead, but if not, he could be on the books to face either Otto Wallin (+275) or Oleksandr Usyk (+500) after that.

BUTTERBEAN

Compared to some of the other big stars in this article Butterbean might seem like an odd choice. He doesn’t exactly stand alongside the greats like Muhammad Ali and Mike Tyson. Butterbean’s story comes with some interesting background, though.

Back in 1998, WWE ran the “Brawl for All” tournament. These were essentially set up as “shoot” matches – real fights to find out who the toughest wrestler in WWE really was.

These fights caused several injuries but one competitor was crowned – Bart Gunn. Gunn got a huge cash prize and found himself matched against Butterbean at Wrestlemania 15.

The problem there was that Butterbean was an actual boxer, and a very good one at that, where Gunn was a pro-wrestler who wanted to be a boxer.  Butterbean ended the fight in thirty five seconds – and that’s why he’s on this list.