There are athletes who are incredibly gifted, and then there are athletes who know they're incredibly gifted. These 20 athletes, in particular, knew how good they were during their playing careers and they weren't afraid to tell everyone about it.

Roger Clemens

Clemens was one of the best pitchers in the history of the game, and he was well aware of that. Some of his cockiness showed when he threw a shattered bat at Mike Piazza in the 2000 World Series. His defiance in the face of steroid allegations also showed he thought he could get away with anything.

LeBron James

LeBron has cooled his smack talk a little bit as he's matured, but during a time in his career, he was one of the cockiest players in the game. Sometimes, when you're as talented as he is, it's hard to not at least be a little cocky.

Alex Rodriguez

A-Rod is cocky on and off the field. He loves talking about himself and his exploits, and the fact he thought he could get away with taking PEDs and lying about it is a prime example of that. Only time will tell if his season-long suspension will humble him at all.

Allen Iverson

One of the best pure scorers in NBA history, AI took cocky to a whole new level. He was even so cocky that he went off about having to practice since he was such a superstar. He certainly backed up his trash talk, but that doesn't mean he ever stopped talking trash.

Kobe Bryant

The Black Mamba accepts nothing short of success because he's quite the perfectionist. As such, he has himself convinced he's the greatest player to ever play the game, and he's definitely right up there. Unlike some of the other guys on this list, his cockiness has helped his game because it contributes to his killer instinct late in games.

Reggie Miller

Reggie Miller's prime was short, but it was filled with trash talk and showing off. He knew he could score in bunches and he would mock opposing players in the midst of scoring surges. Miller isn't quite as good as some other cocky NBA superstars, but he's definitely as cocky.

Tiger Woods

Even though he doesn't have much to brag about nowadays, Tiger Woods is among the cockiest athletes in sports. When he doesn't play well, he goes off on himself and says how he's so much better than how he played in the press conference after the round. Increasingly, it's becoming evident he's not that good anymore, though.

Randy Moss

Randy Moss was such an entertaining player to watch in large part to his cockiness. He would showboat any time he got into the end zone, which was a lot. His cockiness got on people's nerves a lot, but most of the time, he was just having fun doing what he loved.

Terrell Owens

TO is another NFL receiver who thought he could do no wrong. During his prime, he was one of the best receivers in the league and he let everyone know it. That's why he took on a life of his own outside of games.

Brett Favre

Favre wasn't as cocky vocally as some of these other athletes, but he played with a swagger. Basically, he led by example and played with a killer instinct and that helped propel his teams to new heights. By that coin, he wasn't quite as annoying as some of the other players on this list.

Michael Jordan

There are some crazy stories out there about just how cocky MJ was. He would taunt opposing players and even players on his own team during practice. He knew he was the best of all time and he didn't shy away from that. You partially have to respect that, and it probably got pretty annoying on occasion as well.

Barry Bonds

Bonds is MLB's all-time home-run leader and he didn't act humbly ever. Perhaps his steroid use fueled his cocky attitude, but he really didn't think he could do anything wrong. He was an extremely impressive player, but his actions off the field tainted his accomplishments on it.

Ricky Henderson

After breaking the stolen base record, Ricky Henderson said, "I am the greatest of all time. Thank you." If that doesn't show how cocky the former Athletics speedster was, then nothing will. He was fast and talented and he took pride in reminding people of those things.

Cristiano Ronaldo

"God sent me to Earth to show people how to play football."Don't lie. If you were living the life of Cristiano Ronaldo, you'd be cocky as hell too. From bagging multiple hotties to consistently impressing on the field, Cristiano is living that life. He may have said some some crazy stuff from time to time, like claiming to be better than Lionel Messi, or saying that he was sent by God to Earth to show people how to play football, but in the end, he backs it all up by leaps and bounds…and overly dramatic flops.

Muhammad Ali

He floated like a butterfly and stung like a bee, and he was the greatest boxer of all time. Ultimately, he paid the physical price, but he was extremely dominant in the ring. In and out of the ring, he talked trash to his opponents and most importantly, he always backed it up.

Shaquille O'Neal

"I'm not worried about facing the Sacramento Queens. Write it down. Take a picture. I'm not going to talk about this all year. When I get back, there's going to be trouble."Shaq is awesome. He's a legitimately funny dude (when he's not sharing a desk with Charles Barkley that is), and he's just goofy and ridiculous enough to get away with some of the wildest trash talk in the history of speech. This. Is. Ether.

Shannon Sharpe

"People say, 'Since you got rich and famous, you've become insufferable.' I say, 'That's not true. I've always been insufferable."'He may be rocking an '80s part in his hair in 2012, but the Super Bowl-winning, HOF tight end for the Broncos and Ravens thinks the world of himself. He's one of the best tight ends to ever play the game, but we'd be hard pressed to find another guy with his combo of a great gift of gab and confidence to boot. He currently serves the "Charles Barkley" role for CBS's football show but over the years he's given us some gems like the meltdown of the year and the Ray Buchanan war of words. Yo Ray "he might got a body" though?

Anderson Silva

"To be honest with you, I really don't like to hurt my opponents; this just happens to be our job. But if somebody disrespects me they will pay for it. I promise."In a sport where you can be yesterday's news tomorrow, Anderson Silva remains a mainstay in mixed martial arts. Even with his notoriously cocky style that includes obnoxiously swaying all around the Octagon and taunting his opponents to no end, The Spider is still capable of defeating all comers, and rather easily at that. In fact, Silva hasn't lost a match since January 2006, so as they say, if it ain't broke, don't fix it. Unless it's one of these. Then yeah, fix it.

Floyd Mayweather, Jr.

"Yup, I'm better than Muhammad Ali. Sugar Ray Robinson? Yup, I'm better than Sugar Ray Robinson. I would never say there's another fighter better than me."Aside from boxing enthusiasts not too many people had heard of Floyd Mayweather prior to the mid-2000s. Sure, he was undefeated back then and had won titles, but after Mayweather left Top Rank promotions in 2006 to become his own boss that's when the world really got to know Pretty Boy Floyd. From his classic 24/7 moments to his other ridiculous rants, Money Mayweather has shown a belief in himself not matched by many other athletes. Unlike everyone else on this list, Floyd has never lost as a professional. The legend (and ego) grows.

Deion Sanders

"Sure we're in limos. We're stars. How else is a star supposed to travel?"He made a rap song about all the money he has, he still refers to himself in the third person, and we love him for it. Prime was flashy, but for good reason. He brought style to the gridiron with his gold chain waving in the wind as he high-stepped his way to another pick-6. Compared to other corners his numbers are a bit diluted because no one ever threw to his side, ever. And the Throne dedicated a song to him. We're done here.