What makes a player revolutionary?

There's no single, definite answer.

Great players are often considered revolutionary. They often cause opponents to change the way they play or develop new strategies to stay competitive.

But great players are sometimes only that: Great players—not revolutionary or innovative in any way.

Sometimes the innovators work in obscurity. Sometimes the people who change the game don't realize what they've done until years, or decades later.

And some are barely famous.

With that in mind, we've compiled a list of 25 players we think revolutionized soccer. You've heard of a few—here's a hint, the first name is Pele—but some of them might be unfamiliar to you.

Whatever the case, these 25 all did something to make the game what it is today.

1. Pele

Any list of revolutionary soccer players must start with Pele.

Period.

The best player of all time, Pele is also soccer's most revolutionary.

From his World Cup debut in 1958 at the age of 17 to the twilight of his career in America, Pele changed the way soccer was played. He brought joy and skill to the sport unlike anything ever seen before.

He won everything he could possibly win. He played better than anyone else. And he even helped popularize the sport in America, the nation most actively hostile to the sport, when he became a superstar with the glamorous New York Cosmos.

If for some reason you're unfamiliar with his work, watch this video.

It will brighten your day.

2. Diego Maradona

If any player ever gave Pele a run for the title of best ever, it was Diego Maradona.

The little, flamboyant Argentine was unmatched as a player in his day. He led Argentina to the World Cup title in 1986 and scored the famous Hand of God goal against England.

That goal was later named Goal of the Century by FIFA, sealing Maradona's place in history.

Also sealing his place in history have been some bizarre antics.

Maradona tested positive for cocaine during the 1990 World Cup. Since his retirement, he's gained weight, lost weight and gained it back at alarming rates. He's also gone off on crazy, obscene rants (scroll to the bottom of the page) about his body parts.

For his unquestioned brilliance and questionable sanity, Maradona must be considered one of the sport's most revolutionary figures.

3. Johan Cruyff

Johan Cruyff led a football revolution in the 70s.

During that decade, the Netherlands, a tiny nation in Western Europe, became one of the world's best footballing countries.

The Dutch reached two consecutive World Cup finals playing a new style called Total Football. Rinus Michels developed and refined the concept, but Cruyff put it into action.

His brilliance led the Oranje to second place in the 1974 Cup (though many consider that team to have been the best in the world that year). He retired from the international game in 1977 after helping his country qualify for the 78 Cup, where it again finished second.

At the club level, he won the Dutch league eight times and the European Cup three times with Ajax, and won the Spanish League title with Barcelona.

He also scored this goal, one of the best of all time.

4. Franz Beckenbauer

To earn a nickname like Der Kaiser, you've got to be revolutionary.

That's exactly what Franz Beckenbauer was.

Beckenbauer is generally regarded as the greatest German player of all time. For a country (we're including West Germany) that has won three World Cups and made the finals of four more, that's saying something.

Der Kaiser started his career as a midfielder before gaining fame as a defender. Later, his versatility led to the creation of a new position, the libero or attacking sweeper:

Those powerful long runs out of central defence had never been seen before. Up to then, no one had thought that a sweeper had any job being in his opponents' half of the field, let alone scoring. Beckenbauer both created and bequeathed this tactic to the modern game. It contained the element of surprise and it became his trademark.

As Keir Radnedge wrote in Soccer: The Ultimate Encyclopedia: "He was the puppet master, standing back and pulling the strings which earned West Germany and Bayern Munich every major prize."

More recently, he helped Germany win the right to host the 2006 World Cup. Germany, of course, made it to the semifinals of that tournament despite fielding what many thought was a young, under-strength squad.

They were just following the lead of their revolutionary Kaiser.

5. Michel Platini

Nowadays, Michel Platini serves as the head of UEFA

But during his playing days, he earned a reputation as one of the world's best passers, free-kick takers and finishers.

As a midfielder, Platini set the record for French national team goalscoring until Thierry Henry broke it in 2007. All those goals helped Les Bleus win Euro 1984 and reach the World Cup semifinals in 1982 and '86.

Platini still holds the record for most goals in a European Championship with nine.

6. Alfredo Di Stefano

Alfredo di Stefano was one of the greatest players at the dawn of the modern era.

Born in Argentina to a family of Italian immigrants, di Stefano represented Argentina, Colombia and Spain at the international level. But he never appeared in a World Cup.

It was at the club level that di Stefano showed his brilliance.

A tall, powerful striker, he led Real Madrid to the European Cup title each of the first five years the competition existed. He scored twice in the inaugural final as Real Madrid beat Stade Reims 4-3.

The Spanish giants have won nine European Cups, the most of any team. That run can be traced back to the days of di Stefano.

7. Ferenc Puskas

It's hard to believe now, but Hungary used to be a world power in soccer.

Ferenc Puskas had more to do with that than anyone else.

Puskas, an inside forward who scored 157 goals in 182 league appearances with Real Madrid, nearly led Hungary to World Cup glory in 1954.

The Mighty Magyars, as they were known, had been unbeaten in 32 games leading up to the World Cup. That run included a gold medal in the 1952 Olympics, back when Olympic soccer meant something.

In the group stages of the '54 Cup, Hungary whipped West Germany 8-3 and South Korea 9-0. In the knockout phase, the Magyars beat Brazil and Uruguay.

But in the final, West Germany upset Hungary 3-2, leading the match to be nicknamed "The Miracle of Berne."

But despite the disappointment, Puskas scored four goals in the tournament, including the opener in the final.

8. George Best

There's a saying in Northern Ireland, the home country of George Best.

It goes like this:

"Maradona good; Pele better; George Best."

At times, Best proved it, too.

A winger, Best was one of the best players in the world thanks to his combination of speed, balance, dribbling ability and goalscoring prowess.

On the field, he had no equal.

Off of it, he was similarly unique. Here are some of his best quotes:

"If I'd been born ugly, you'd never have heard of Pele."

"They say I slept with seven Miss Worlds. I didn't. It was only four. I didn't turn up for the other three."

"Footballers today are millionaires by the time they're 22 or 23. More and more of them are going out and looking for something to give them a buzz outside football, be it gambling, drugs or booze. I got my buzz from playing. Players now have a groin injury for months and months and I often think they don't really give a toss whether they're playing or not because they're getting paid anyway."

More on that later. For now, let's give Best his due: He led Manchester United to the 1968 European Cup and two league titles.

He also revolutionized the game with his skill and personality.

9. Eusebio

Eusebio was so good, he had three nicknames.

Called the Black Panther, the Black Pearl and The King, Eusebio earned the right to have three nicknames with 733 goals in 745 career matches. Playing with Benfica in his native Portugal, he won 11 league titles, five Portuguese cups and one European Cup.

He scored nine goals at the 1966 World Cup as Portugal advanced to the semifinals. He didn't play in another Cup and Portugal failed to qualify again until 1986.

10. Bobby Charlton

If we're talking about Eusebio, Bobby Charlton must be included.

Charlton, who played for England and Manchester United, was one of Eusebio's rivals. The two players and their teams squared off in the 1966 World Cup semis, with Charlton scoring and England getting the win.

England went on to win the World Cup. That still hasn't happened again.

That summer, the home country of soccer finally brought home the game's most prestigious prize. Charlton was perhaps their best player during that run.

11. Gerd Müller

Gerd Müller wasn't the most physically imposing striker.

But for a while, he was the best.

At 5-9, Müller beat bigger, stronger defenders consistently throughout his career for both Bayern Munich and Germany. At the club level he scored 398 league goals in 453 appearance. For Germany, he scored 68 times in 62 caps.

That's more than one goal per game.

When he retired, he was the World Cup's all-time leading goalscorer with 14. Want to know who broke the record?

Go to the next slide.

12. Ronaldo

No, not Cristiano Ronaldo.

This Ronaldo—the original—led Brazil's most recent resurgence in the late 1990s and 2000s. After sitting on the bench for the Sambas in their triumphant 1994 World Cup campaign, he played a starring role as a 21-year-old in 1998.

He scored four goals and had three assists as Brazil advanced to the final against host France. The night before the match, Ronaldo suffered a mysterious convulsive fit. The next day, he was out of sorts, Zinedine Zidane was brilliant, and France won 3-0.

In 2002, however, Ronaldo was the World Cup's top scorer with eight goals as Brazil won its fifth title. He scored both goals in the Sambas' 2-0 win over Germany in the final.

Along the way, Ronaldo became a worldwide sensation for his goofy grin, gap teeth and fluctuating weight. Nonetheless, he was named European player of the year (Ballon d'Or award) twice and FIFA World Player of the Year three times.

And he finished his career as the all-time leading World Cup scorer with 15 goals.

13. Eric Cantona

Eric Cantona is well known for a few things. Not all of them are good.

There's the famous kung fu kick.

There are all the famous quotes.

And there's his unquestioned, nonchalant brilliance.

(What's up with the commentary on that video?)

He also convinced a generation of American youth players to pop up their collars while they were playing. That includes this writer.

It doesn't get much more revolutionary than that.

14. Zinedine Zidane

Remember when we talked about a brilliant Zinedine Zidane in the 1998 World Cup final?

Here's the evidence.

It's hard to know whether Brazil could have won with a fully fit Ronaldo that day. Zidane played an inspired form of football over 90 minutes that rarely have been replicated.

Zidane was the world's best that day. He was the world's best in his prime.

He was so good, even Brazil couldn't beat him.

15. Lothar Matthäus

Lothar Matthäus was so good and so versatile for so long that he played top-class football into his late 30s.

In 1990, he helped lead Germany to its third World Cup. For his role, Matthäus won the Ballon d'Or for European Player of the year and was named World Soccer Magazine's World Player of the Year.

Nine years later, he was voted the Bundesliga's top player at 38 years old.

Before retiring in 2000 following a spell in MLS, Matthäus had played in 25 World Cup matches over five tournaments (both records), won Euro 1980 and been capped 150 times by his country.

16. Dennis Bergkamp

In his prime with Arsenal and the Netherlands, Dennis Bergkamp could control the ball better than any player in the world.

Watch his amazing ball skills in this superb individual goal.

Then admire his passing, field awareness and control in this great team goal.

Defense had to adjust their tactics to deal with Bergkamp, who loved to drop from his striker position into the midfield. With his club team, Arsenal, that allowed Thierry Henry the space he needed to develop into a lethal striker.

Bergkamp, though, could unlock a defense better than anyone.

17. Jose Nasazzi

Before Uruguay's recent renaissance, most people had a hard time believing the tiny South American country had once been a global soccer power.

But that's exactly what Uruguay was in the early days of the World Cup. And Jose Nasazzi was perhaps their best player during that time.

Uruguay won the inaugural World Cup in 1930, and Nasazzi served as captain.

Known as "El Gran Mariscal" (The Great Marshal), Nasazzi also led his country to glory at the 1924 and '28 Olympics (back when the Olympics meant something) and Copa America in 1923, '24 and '26.

Nasazzi's influence lives on to this day with Uruguay's national team. The most recent squad to beat Uruguay in a competitive match (right now it's the Netherlands) holds "Nasazzi's Baton," an official title that recognizes the importance of the original World Cup champions.

Uruguay won the first World Cup. Nasazzi was the driving force behind it.

18. Gaetano Scirea

In Italian calcio, defense rules.

For decades, the Italians played catenaccio, a form of defense that translates into English as something like "door-bolt."

That should give you the appropriate mental image.

The system launched the careers of several all-time great defenders and helped Italy win the 1982 World Cup.

For our money, Gaetano Scirea was the best of the bunch. As the libero or sweeper, he was the rock of both Italy's and Juventus' defenses.

Catenaccio revolutionized the sport. Scirea was perhaps its best practitioner.

19. Lev Yashin

Nicknamed the "Black Spider," the Soviet Union's Lev Yashin is widely considered the top goalkeeper of the 20th century.

He combined athleticism, superior size, strong reflexes and innovation to become the best.

His biggest contribution to the game is goalkeeper sweeping, a strategy all modern keepers use. Before Yashin, goalkeepers sat back in their goal and let the offense come to them.

Yashin changed that. He started acting like another defender, punching, kicking and heading away balls that came into his box.

It's likely that someone else would have come up with the idea eventually. But Yashin did it during his peak in the 50s and 60s.

During that time, the Soviet Union won Euro 60, and Yashin's club, Dynamo Moscow, won five league titles.

20. George Weah

George Weah makes this list not only for what he did as a player.

He makes the list for where he came from.

Weah, who rose to stardom after growing up in the slums of Monrovia, Liberia, was named FIFA World Player of the Year in 1995. He was the first—and still only—African to earn the honor.

One day, that will be a watershed moment in soccer.

When an African team finally wins a World Cup—and it will happen—we'll look back to Weah as a trailblazer.

An interesting aside: Weah's first European club was AS Monaco, which signed him in 1988. The manager that brought him in? Arsene Wenger.

21. Brandi Chastain

Yes, Brandi Chastain.

Be honest: You remember that picture, don't you?

You remember exactly what Chastain was doing in her sports bra in front of 90,000 people, right?

And that was the first time you cared about women's soccer, wasn't it?

Most of the American population will answer yes to all three questions. That makes Brandi Chastain revolutionary.

Here's the story. The United States and China played to a tie in the 1999 Women's World Cup final at the Rose Bowl in Pasadena, California. Chastain scored the winning penalty and spontaneously ripped off her shirt in celebration.

It launched the US team from the realm of plucky, fringe-sport stars into the cultural mainstream.

Twelve years later, the US players again became cultural icons during their run to the 2011 World Cup final. That run might have happened without Chastain and her sports bra, but their stardom probably wouldn't have.

22. Mia Hamm

But we can't talk about women's soccer without Mia Hamm.

Mia Hamm is the greatest player in women's soccer history. And she has inspired millions of American girls to play the sport.

During her playing career, she led the University of North Carolina to four national championships, helped win two World Cups and scored 158 international goals in 275 appearances.

But her biggest contribution to the sport has been more lasting. Since 1999, soccer has exploded as a participation sport in America. Millions of young girls started playing because of Hamm.

And when they become mothers, their kids will probably play, too.

23. Landon Donovan

While we're on the subject of American soccer, let's talk about Landon Donovan.

Landon Donovan isn't the most naturally talented player in American soccer history. Guys like Claudio Reyna, Tab Ramos and, heck, even Freddy Adu, come to mind.

Landon Donovan's pro career hasn't been a complete success. He failed twice in Germany and only seems comfortable in the safe haven of MLS.

But here's the thing: Donovan is an internationally respected player. People around the world know who he is.

And soccer fans in Europe, South American and everywhere else respect him.

The US has never had a player like that before. It's not quite accurate to call him America's first international superstar, but it's fair to say he's earned more respect than any other American.

24. Paul Caligiuri

Who?

Paul Caligiuri is a player who had a middling pro career after playing collegiate ball at UCLA. In 1989 he found himself playing for a middling United State's Men's National Team against Trinidad and Tobago.

So why is he revolutionary?

Easy: He scored the only goal in his country's 1-0 win over Trinidad that day. The win clinched qualification for the 1990 World Cup.

The US had not reached a World Cup since 1950. But since 1990, the US hasn't missed a World Cup.

And since then, the American game has experienced unprecedented growth. The World Cup came to the States in 1994 and a league followed in 1996. Today the league is flourishing and millions of kids play and follow the sport.

The Cup and the league both had been agreed on before Caligiuri's goal. But by qualifying for the 1990 World Cup, the US team set off a chain of events that made the sport relevant in America for the first time.

Eventually, we think the US will win a World Cup. The country has the resources and the population. Now it's a matter of training and developing players, tactics, methods and philosophies.

The hard part is done. Caligiuri made sure of that.

25. David Beckham

David Beckham makes the list not because of his playing abilities.

Beckham makes the list for his cult of personality.

Back in the olden days, footballers were footballers were footballers. They played football. They went out for beers. They were normal guys who earned a bit of celebrity for playing a tough game.

Modern soccer couldn't be much different. The players are millionaires. They're worldwide celebrities. In addition to being famous for playing soccer, they become famous for being famous.

It all started with Beckham.