What is hard play and what is dirty play? Like many athletes, Pittsburgh Steelers linebacker James Harrison struggles to discern the difference. "I don't want to see anyone injured, but I'm not opposed to hurting anyone," he said. "There's a difference. When you're injured, you can't play. But when you're hurt, you can shake it off and come back. I try to hurt people." In that spirit, FOXSports.com presents the dirtiest athletes in sports today.

The maniac formerly known as Ron Artest, who triggered the "Malice in the Palace" (ironically, considering his new last name), is trying to toe the line these days. He told reporters before the 2010-11 season that he's sworn off booze and marijuana and has made a conscious effort not to stay unglued. "I try to be as smart as possible and as aggressive as possible without being ejected." But World Peace is still no fun to play against. He was suspended six games during the 2011-12 season after elbowing James Harden in the head, and players he defends still never know what to expect. That's why he trailed only Reggie Evans in "dirtiest player" voting for a magazine's poll on NBA players.

His volcanic temper cut short his collegiate career. Excessive penalties for post-whistle skirmishes prompted the St. Louis Rams to cashier him. The last straw: a pair of head-butting fouls in a game at Tennessee. "You know, like the FBI's 20 Most Wanted? Yeah, he'd be on that list," former NFL linebacker Julian Peterson once said. Incognito passed through Buffalo and landed in Miami, where the Dolphins are keeping him on a short leash ... so far, anyway.

No defenseman is better in his own zone. Not coincidentally, no defenseman is nastier with his stick. Pronger is a master of medieval arts — hooking, slashing, cross-checking or high-sticking. That's is why colleagues honored the Philadelphia Flyers captain as the league's dirtiest player in separate magazine surveys. It's hard to single out one Pronger highlight, but stepping on the calf of injury-prone Vancouver Canucks center Ryan Kesler (no angel himself) was a classic move.

His tackles have left a trail of fallen players, including US midfielder Stuart Holden (broken leg) and Newcastle winger Hatem Ben Arfa (broken tibia and fibula). So Netherlands coach Bert van Marwijk felt compelled to drop De Jong (left) from the national squad. He told Dutch daily Algemeen Dagblad that the Ben Arfa tackle was "unnecessary and wild," adding that he has "a problem with the way Nigel needlessly looks to push the limit."

His penchant for throwing at hitters and a pair of incidents with former teammate Mark Teixera prompted the Texas Rangers to put him on waivers. When he plunked Kurt Suzuki in his next start, the Rangers designated him for assignment and ate $8 million in salary. Former Los Angeles Dodgers manager Joe Torre vowed to keep him in line, but Padilla broke Aaron Rowand's face with a beanball in 2010. "I threw inside and the pitch ran in on him," Padilla explained at the time.

Margarito lost his boxing license in the wake of his January 2009 bout with Shane Mosley. A pre-fight inspection found a plaster-like substance in his hand wrapping. The substance was removed, and Margarito lost in a knockout. His trainer Javier Capetillo earned a lifetime ban from U.S. boxing. Margarito pleaded ignorance and later got a Texas boxing license.

He cultivates a nice-guy image off the track, but cross him on the track and he'll go to extremes to get even. Fellow driver Ryan Newman offered this view of Edwards: "We can get in each other's faces. That's 'have at it boys.' Going out there and purposely crashing somebody ... is not at all 'have at it boys.' Some people have thought of manslaughter or attempted manslaughter, but that's closer to what it is."

He established his reputation by earning a 20-game suspension for crushing former NHL player Dean McAmmond — during a preseason game no less. He once punched out a junior hockey teammate's teeth during practice after the teammate refused to participate in a hazing ritual. But Downie can play, too, as he showed in 2009-10, scoring 22 goals and earning 208 penalty minutes, the NHL's first 20/200 season since 2001-02.

Lambert became an Internet sensation by detonating during a match against BYU in 2009. Her forearm smash in the back of an opponent wasn't out of the ordinary, but this ponytail yank was another matter. She also took out the legs of opposing players and landed some head slaps. The school suspended Lambert, but later welcomed her back for her senior season. She also served a two-game Mountain West Conference suspension.

This speedy outfielder's antics led to his eventual trade from the Washington Nationals. He once threw a ball into the stands that hit a fan in the head. He bulldozed Marlins catcher Brett Hayes on a play at the plate. He rushed the mound and instigated a bench-clearing brawl. All this added up to an eight-game suspension. His explanation: "I'm a hard player. It's just going out there and playing the game ... I'm just sticking up for myself and defending my teammates."

Helmet-to-helmet shots a no-no in the NFL these days, a fact that make's the reigning "NFL's Meanest Player" a bit upset. In 2010 when the league fined Harrison $75,000 fine, the Steelers LB actually threatened to retire. Although Pittsburgh has other players considered nominees for the dirty dozen — including receiver Hines Ward — Harrison makes this list for having no regrets.

In 2006, video footage captured Evans reaching below the belt to grab Chris Kaman's manfruit. Sam Cassell, a guard with the Clippers at the time, couldn't believe what he saw. "When I saw it on TV, it was like, 'Wow,'" Cassell said at the time. "You know what, Reggie is a good guy. I think he just lost it for a minute." Yeah, well, Evans loses it often. He was the landslide "dirtiest player" winner in a 173-player magazine poll in 2012.

Since coming into the league in 2010, the Detroit Lions defensive tackle has been one of the NFL's most controversial players. One magazine poll of fellow players, in fact, named Suh as "the dirtiest player" in the NFL. And there are quite a few examples to prove that claim. During a 2011 Thanksgiving game against the Green Bay Packers, Suh pushed Evan Dietrich-Smith's head into the ground three times before stomping on his arm. It was the fifth time Suh had been disciplined by the NFL for on-field conduct, and it led to a two-game suspension without pay. A year later, Suh caused more of a raucous after contacting Houston Texans QB Matt Schaub's groin area with his cleat during another Thanksgiving game. While he avoided suspension from the league for the play, he did receive a $30,000 fine.

Even after his third NBA suspension of 2012, for fighting Nets forward Kris Humphries, the Boston Celtics point guard insisted that he isn't a dirty player. Try telling that to Bulls guard Kirk Hinrich, who Rondo tossed into the scorer's table during a 2009 playoff game. Or Heat star Dwyane Wade, who he clotheslined in the 2012-13 season opener. Or the ref he intentionally bumped during a playoff game last season. Or the other ref at whom Rondo fired a basketball following a foul call. Call him feisty, emotional, chippy and extremely talented. But call him dirty, too. He's probably the only one who disagrees.