There's no doubting that it's cool to be a football fan.

But some teams are simply "cooler" than others to support.

The reasons and forces that define coolness are varied.

Maybe it's the rich history of a club; maybe it's their current philosophy or something they stand for; maybe it's simply part of the fanbase and their actions.

Whatever the case, clubs are cool to support for many different reasons, and the 10 mentioned in this list are certainly pretty cool indeed. Read on to see which clubs make the list, and which club takes top spot.

10. Celtic FC

Few clubs exist in world football with the same history as Celtic FC.

Having been established in the late 1880s, the Hoops have won the Scottish League Championship a staggering 44 times, the Scottish Cup 36 times and the Scottish League Cup 14 times. Plus, they won the European Cup in 1967 (along with everything else available that year).

The "coolness" of Celtic certainly comes with their history of strong success (having never been relegated to a lower division) but also in their rivalry and passion.

Few rivalries exist as great as the Old Firm between Celtic and Rangers.

9. Sao Paulo FC

Like Celtic FC, Sao Paulo FC have never been relegated from the top tier of Brazilian football, and they've established a legacy as one of the country's top teams.

The number of stars who have played for the Brazilian club is simply staggering, with Sao Paulo having seen the likes of Lucas Moura, Fernandinho, Wellington, Miranda, Denilson, Cicinho, Hernandes, Luis Fabiano, Kaka, Palhinha, Edmilson and Serginho play for them in the past few decades.

And who could forget goalkeeper Rogerio Ceni, who has featured at the club since 1990—making over 1,100 total appearances and scoring over 100 goals?

Yup, that's right: over 100 goals from a goalkeeper.

8. S.L. Benfica

Founded just after the turn of the 20th Century, S.L. Benfica is one of the biggest and most reputable clubs in not only Portugal but right across Europe as a whole.

In fact, Benfica lay claim to being the world's most supported football club, and while that might be a little tough to measure precisely, there's little doubt that the Portuguese club are certainly in contention thanks to their incredible history of domestic and European success.

Da Luz boasts an incredible atmosphere for Benfica, and for obvious reasons.

Benfica once went 58 games without defeat in the Portuguese Primeira Liga throughout the late 1970s and have never been relegated from the top flight.

Eusebio's brilliance throughout the 1960s not only saw him score 474 goals for the club in 440 matches but also saw Benfica dominate in many competitions—making five European Cup finals (winning two), winning eight Portuguese Championships and three Portuguese Cups.

From 1960 to 1977, Benfica won 14 from a possible 18 league titles.

7. Arsenal

Regardless of how many days it might have been since Arsenal last won a trophy, there's little doubting that the Gunners are an incredibly cool club to follow.

Not only are they top of the Premier League (and reaping the rewards of Mesut Ozil's arrival), but they've made it there because of something other than money. Arsene Wenger has patiently built a world-class squad and worked his talent, and that's made the club's fans incredibly grateful for his ingenuity but also incredibly passionate and loyal to the club's cause.

The list of players to have donned the red and white colours at Arsenal goes on and on, with the likes of Thierry Henry and Dennis Bergkamp simply two in a long list.

It's unlikely that the Invincibles' achievement will ever be bettered.

6. Galatasaray S.K.

"Welcome to Hell."

That's become somewhat of a tagline for Galatasaray over the years courtesy of their passionate fans and the incredible atmosphere that they provide at the Turk Telekom Arena. After all, how many grounds can claim to have had a Guinness World Record for the loudest roar at a sport stadium?

Galatasaray became the first Turkish team to win a European trophy in 1999 (as they went unbeaten in their UEFA Super Cup run) and became the first Turkish team to rank first in the IFFHS World Rankings.

They're also one of a few clubs in the world who can lay claim to winning the "quadruple" in 1999/2000 when they won the Turkish Super Lig, the Turkish Cup, the UEFA Cup and the UEFA Super Cup, plus they've never been relegated from the top-flight competition.

5. Athletic Bilbao

Athletic Bilbao: Cue "never been relegated from the top flight" once again.

Bilbao's Basque roots mean that, unlike other clubs, they are always looking to promote young players who have come through the ranks. They only include Basque players in their squad and, as a result, have built an identity that few clubs in world football will ever match.

Oscar de Marcos famously said, via Tom Conn of Inside Spanish Football, that "being a part of Athletic Bilbao is a religion."

An incredibly powerful—and cool—statement indeed.

4. Borussia Dortmund

One of the more recent "cool" clubs, it's hard not to like Borussia Dortmund.

Form Jurgen Klopp's extrovertness to the Yellow Wall that simply makes the Westfalenstadion such an imposing ground, Dortmund have quickly become the "cool" club to follow nowadays, with their success in both Germany and Europe as a whole certainly helping also.

Just watch this video. How can't you have a soft spot for this club?

3. Boca Juniors

Having won more than 50 titles to date, there's little doubt that Boca Juniors is one of the most prestigious (and therefore cool) clubs throughout world football.

The Argentinian powerhouse were named by IFFHS as the top South American club throughout the past decade, and their rich history of success has continued to draw many more fans to them—despite the fact that the club might not be traveling as well as in previous years.

Their youth academy is one of the best in South America, while their involvement in the Superclasico with River Plate alone makes them an iconic club to behold.

The blue-and-yellow kit is one of the most iconic kits of all time.

2. FC St. Pauli

Any club whose logo includes a skull and crossbones is pretty cool.

FC St. Pauli are perhaps the closest thing to a cult in world football, with their fans up there with the most diehard in world football. The punk-rock-esque club also proudly boast one of the biggest female fanbases in world football due to their anti-racist, anti-homophobic and anti-sexist nature.

Currently residing in second-division Bundesliga, St. Pauli are pushing for promotion once more in third place and would certainly make a scene if they do indeed make it back to the top-tier league.

They haven't been in the Bundesliga since the 2010/11 season when they went winless in their final 13 games of the season to finish bottom of the ladder.

On the wrong end of an 8-1 drubbing from Bayern Munich in their final home game of the year, St. Pauli fans were ecstatic when Marcel Eger scored to, at the time, take the score to 5-1. Any fanbase that can cheer in the midst of relegation and a thrashing from Bayern Munich deserves some applause in my book.

1. SSC Napoli

Perennial underdogs with a glorious, spectacular history. That's the best way to describe S.S.C. Napoli and it's the reason why they've taken the top spot here.

Grantland's Bryan Phillips called Napoli, "A team of crazy highs and pulverizing lows — basically the entire sports-fan experience in its most extreme and operatic form, all compressed into one club in a terrifying and fascinating city on a gulf at the foot of a volcano."

Try to top that.

The club have been to bankruptcy and back in the past decade and are finally starting to build their reputation once more as one of the best clubs in Italy. 

After all, they are the home of Diego Maradona, whose unveiling at the club in 1970 still remains one of the most spectacular sights in the history of world football.

Nowadays, Napoli are vying for top spot in Serie A alongside a number of other clubs. Yet whatever the result, they know that their fans will remain as loyal as ever.

And they certainly won't lose their voice, either.

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