If there is one thing that professional sports franchises cannot do without, it's their fan-bases. A fan-base is the lifeblood of any team, no matter what professional league, no matter what sport or what city they are in.

In the monetary sense, fans are important for the very simple reason that they are one of the primary ways teams make money. They buy the tickets and fill the seats of stadiums and arenas. They buy concessions that keep them fed and, often times, well inebriated while watching their favorite team. They buy jerseys, hats, and other memorabilia to show their support for favorite players. All this, in turn, leads to TV deals and sponsorship money that has seen salaries and revenue skyrocket across major North American and European pro leagues.

In a more meaningful sense, though, the fans of a team can play a much more significant role than as paying customers. They are there to rally their team when they need a boost of adrenaline. They are there to celebrate the good times and cry for the bad. They are there to intimidate opposing teams coming into their building, and they are there to give a stern talking to (usually through boos and throwing of objects on the playing surface) when their team is not performing at the level they should be. Professional sports would be nothing without fans.

In turn, some fans would be nothing without their teams. There are all kinds of different types of fans and overall fan-bases, and while we might classify these fan-bases as the "craziest," what we really mean is that they are the most invested and passionate groups of fans that you'll find in the world of sport. In my book, that's something to be proud of and a label that any fan-base can carry with pride.

Who wouldn't want to play in front of one of these raucous crowds?

15 15. NASCAR

For one thing, you have to have a little bit of craziness in you if you're idea of a good time is sitting in 100 degree weather with the sun beating down on you while you watch cars go in circles hundred of times (albeit at ridiculously high speeds). It's a whole new level of crazy when you go just to see the cars wreck, while accepting the risk that pieces of those cars may very well fly at you during a crash. You have to give it up for those die-hard NASCAR fans, they sure do love their racing.

14 14. Montreal Canadiens

Montreal Canadiens fans are unique in a couple of ways. It happens in every city, but it seems to be more pronounced in a city with only one of the Big 4 North American leagues present on the local sports scene. Everyday, every move, play and decision is analyzed with the attention surgeons give to the heart they are about to perform a triple-bypass surgery on. Not only that, Habs fans have been known to riot not only for losses, but also victories and suspensions. There we Tebow-like rallies outside the Bell Centre for Alexei Kovalev a few years back, and Saku Koivu was once ambushed by photographers while sitting in a hospital bed wondering whether he'd ever see out of one of his eyes again. If the word to describe hockey fans in Montreal isn't "crazy," I'm not sure what is.

13 13. Pittsburgh Steelers

Steelers fans often fall into the category of "obnoxious" because they flaunt their six Super Bowl championships more than Floyd Mayweather flaunts his millions upon millions of dollars. They fall into the crazy category because of the atmosphere fans create at Heinz Field on a regular basis; Terrible Towels aside, they are an intimidating fan-base to deal with as an opposing team coming into town. The Steelers have always had the image of a rough-around-the-edges, hard-nosed football team, and their fans personify that image to a tee.

12 12. St. Louis Cardinals

This selection may surprise you, because no one ever thinks about St. Louis as a place with voracious, wild crowds or lunatics in bird hats wreaking havoc at Busch Stadium. That's because these fans are usually wreaking havoc elsewhere. Cardinals fans are widely known as some of - if not the best - travelling fans, not only in baseball but in all of professional sports. You have to be a little bit crazy to follow your baseball team around as if you were a groupie on tour with a rock band.

11 11. Nebraska Cornhuskers

What the Nebraska Cornhuskers lack in the intimidation department (on account that they have decided to go with corn as their association of choice), they make up for with a ridiculously passionate and crazy fan-base. The team has sold out every single home game since 1962, and you'd be considered out of place if you didn't walk into Memorial Stadium without a giant corn hat on your head.

10 10. Seattle Seahawks

While the Seahawks are often the focus of bandwagon jokes, a fair amount of credit should be given to the longstanding fans of the great city of Seattle. Until recently, the Seahawks were never the team with a whole lot of "pop," but now the loyal fans who stuck with the team are finally being rewarded for their patience. The "12th Man" fan-base has already carved out a spot as one of the greatest fan-bases of all time, considering the fact that they very nearly cause earthquakes at every game and forced the NFL to implement a noise rule (which they still break every game to this day).

9 9. Duke

The Duke Blue Devils basketball program is one of the best-run college programs in the entire NCAA and their ultra-passionate fans, the "Cameron Crazies" are just as legendary, not to mention as organized and well-prepared as Mike Krzyzewski's players. The Crazies are known to have some of the best chants and heckles for opposing players, always ready with a new chirp to rattle the opposition. No opposing team walks out of Cameron Indoor Stadium without a bit of a bruised ego and steam coming out of their ears.

8 8. Borussia Dortmund

The sea of yellow you'll find at a Borussia Dortmund match is as stunning an image of a fan-base as you'll find in sports. The club is often considered the "B team" of fans globally simply because it's easy to want to be a part of the atmosphere that manifests itself at one of their games. At any home game, there are close to 25,000 Borussia Dortmund supporters in standing room only sections, sections that could be upgraded to create more revenue, but haven't been because the atmosphere would suffer.

7 7. Boston Fans

It was too difficult to narrow it down to one Boston team, so we threw them all into the same category. Bruins fans are the rowdy, loud and bashful crew that will slug it out with anyone who talks down about their team. Celtics fans bask in the glory of past success and still hang onto the Kevin Garnett credo "ANYTHING IS POSSIBLE!" - and lest we forget the craziest of them all, the "Fenway Faithful," who create an ballpark atmosphere like no other with their songs and game-day rituals.  Even the security guards get in on the fun at Fenway.

6 6. Liverpool

One of the most famous clubs in the history of English football, and one of the most recognizable brands in the world of sports, Liverpool supporters have long been considered part of the discussion as the wildest and most passionate football fans on the planet. Just ask Mario Balotelli, who quite literally received a hero's welcome in his arrival to the club this week. They are some of the loudest and proudest in England, to the point where even officials can be intimidated by the brash supporters of The Reds.

5 5. New York City Fans

If you watch Family Guy, you'll remember the episode where the "Leafers" (New Yorkers who flock to Massachusetts to see the leaves change color) invade Quahog and pretty much take over the city. In an attempt to rattle the New Yorkers in his favorite bar, Peter Griffin simply stands in the middle of the pub and says "Jets suck, Yankees suck, Knicks suck." As you would expect, they all got up and rushed at the ill-speaking Boston fan.

This scene pretty well sums up the New York fan. Passionate, obnoxiously loud and crude, these fans are by far the easiest to get going. Just say something bad about one of their teams and their passion usually leads to quite a bit of angry yelling and sometimes fisticuffs.

4 4. Boca Juniors

If you're just tuning into the soccer world in general, one thing that may (or may not) surprise you is that South American soccer fever is huge. A good example of this comes from the working-class region of La Boca in Buenos Aires, Argentina, where the "Boca Bosteros" create a fiery atmosphere (literally and figuratively) at every game - which probably makes it difficult to see the game, but definitely creates a unique and threatening atmosphere for opposing clubs.

3 3. Celtic FC

Despite all the fame, glory and respect the big European football clubs get, you'd be hard-pressed to find a more passionate, emotional and crazier fan-base than you would at Celtic Park. The team has a long-standing tradition in the Scottish Premiership and their fan-base is just as legendary, often drowning out the sound of commentators with their loud chants and constant jumping up and down in unison while the game is ongoing. Even their celebrity fans are more passionate than anyone else, as Rod Stewart literally wrote a song about them and wept when they beat Barcelona a few years back.

2 2. Philadelphia Fans

Philadelphia Eagles fans could have easily taken one of these spots alone, but once you throw in the unruly Flyers fans and the knowledgeable but brash Phillies fans, you have an elite city-wide fan-base that is nearly unparalleled across the United States. You better be on the top of your game at all times if you play for a Philadelphia based team, because you'll either hear about it or get pelted in the side of the head with a snowball for it. Not even Santa Claus is safe in an unhappy Philadelphia crowd.

1 1. Oakland Raiders

The Oakland Raiders fan-base lands on the top of this list because if there was any fan-base that truly and fully encapsulated the definition of the word "crazy," it would be those who rock the Silver and Black. Every game-day looks like a Halloween convention, and Raiders fans are raised and bred from a young age to be the most intimidating, wild and raucous band of supporters you'll find anywhere in the world. There is literally only one nation in all of sports and that is the Raider Nation. We at TheSportster implore you not to simply attach "nation" to the end of your team name and claim to be a member of a crazy fan-base. There is nothing tamer than a Toronto Maple Leafs crowd, so hearing "Leafs Nation" is a mockery.