On the field, they stand alone. They train separately, prepare and dress differently and, once the action begins, their target is to thwart the very object of the game: scoring goals.
That every goalkeeper is a little mad can be debated; that they are a breed unto themselves is beyond dispute. Yet even within this exclusive and eccentric club, there exists an elite and especially conspicuous faction: the veterans.
These are the keepers who have survived decades in football's most stressful and arguably most important position, dealing with the taunts of fickle fans while avoiding at all costs the conclusion that they retired a year too late. Some do cling on to the gloves longer than they should, but there are plenty of others whose ability is not compromised by their longevity, and some who actually seem to improve with age.
Lev Yashin, arguably the greatest ever, proved something of a pioneer in this respect by excelling at the 1966 FIFA World Cup™ just months before celebrating his 37th birthday. Yet even the 'Black Spider', who returned to the game's biggest stage four years later, could not rival Dino Zoff in setting the standard for veteran No1s.
The legendary Italian, third only to Messrs. Maldini and Cannavaro in Azzurri appearances, still holds one of his position's most prized records, having gone an unsurpassed 1,142 minutes without conceding in international competition between September 1972 and June 1974. Yet Zoff is, of course, considerably more famous for leading his country to FIFA World Cup glory in 1982 at the ripe old age of 40, a feat achieved 21 years on from his Udinese debut.
History is littered with these great goalkeeping veterans. Peter Shilton, for example, was already England's most-capped player when he became their oldest-ever captain at Italy 1990, while fellow countryman Gordon Banks was still playing for Fort Lauderdale Strikers into his 40s.
In Germany, Sepp Maier started 422 consecutive matches for Bayern Munich - 473 in all - while Frenchman Jean-Luc Ettori retired at the age of 39 only after setting a top-flight record of 602 appearances, all of which came in the colours of Monaco. The Italian Walter Zenga, whose FIFA World Cup record of 518 minutes without conceding still stands, was still turning out for New England Revolution at 39, while Wales and Everton icon Neville Southall made a comeback for Rhyl in his homeland as recently as last year - at the age of 48.
Kahn and Ballotta take different paths
Encouragingly, there is also no indication that goalkeeping's golden oldies are a dying breed. Nor, it seems, are they content to quietly wind down their careers - certainly not if the example of Oliver 'King' Kahn is anything to go by.
Kahn will have retired by the time he turns 39 on 15 June, but his final season has witnessed him lead Bayern Munich to the cusp of an historic treble, and he has also found time to aim the odd trademark broadside at targets ranging from his own star team-mates to the club's incoming manager, Jurgen Klinsmann.
"Kahn always had this incredible force: he wants to win, he always wanted to win," said Winfried Schaefer, who coached the 'The Titan' at Karlsruhe two decades ago. "
His ambition even today distinguishes him from other players
With more Bundesliga games (548) and clean sheets (194) than any goalkeeper in history, Kahn has continued to rack up fresh milestones, recently becoming the first player in history to win six German Cups before moving on to the brink of a record-equalling eighth top-flight title. Club president Karl Heinze Rummenigge recently described the snarling old warrior as "Bayern's gene personified", and no-one doubts that the man once named Europe's top goalkeeper four years in succession will leave a gaping void on and off the park when he departs the stage this summer.
While Kahn himself claims to be looking forward to retirement, a Serie A contemporary six years his senior is adamant that this current, record-breaking season will not be his last. "
I will play another year. I am enjoying myself too much
," Marco Ballotta said recently in the wake of turning 44.
The irony with Ballotta's situation is that, but for a lengthy delay in River Plate youngster Juan Pablo Carrizo obtaining an EU passport, this veteran's belated stint in the spotlight would likely never have come. As it is, a goalkeeper whose professional career began a quarter-of-a-century ago has become the UEFA Champions League and Serie A's oldest player, smashing records held by countrymen Alessandro Costacurta and Zoff respectively.
Such achievements have not, however, shielded him from criticism, and the former Treviso keeper once again came under scrutiny at the weekend after conceding five goals away to Juventus. Fortunately, age has been accompanied by a philosophical outlook. "For many people, when I make a good save it's because of my experience - when I make a mistake it's because I'm too old," Ballotta observed. "I should have stopped ten years ago but I have played another ten. Every year I say it will be my last but in the end I always return in goal."
*Pfannenstiel's claim to fame * This enduring love of the game is to be applauded, and it is by no means a unique explanation for remaining between the sticks, with USA legend Tony Meola another prime example. Such is the enthusiasm of this veteran of 100 caps and three FIFA World Cups, in fact, that at 39 he can still be found keeping goal for the New Jersey Ironmen in US indoor league the MISL.
Argentina, meanwhile, has its own celebrated elder statesman, Carlos Navarro Montoya, a 42-year-old Boca Juniors icon who, despite sustaining a serious knee injury while on top-flight duty for Olimpo last season, remains adamant that he will play on.
Lutz Pfannenstiel also merits a mention, although at 35 the German would be considered a mere child in such company. While hardly a world-renowned name, Pfannenstiel holds the unique distinction of having played for clubs in all six continents, with experience in nations as diverse as Malaysia, New Zealand, Albania, Canada and Brazil.
Finally, it would be unforgivable to conclude any tribute to veteran goalkeepers without recognising one of the position's most charismatic exponents. It may be over 12-and-a-half years since he shocked the world with his 'scorpion kick' at Wembley, and the records will tell you that his 42nd birthday is just four months away, but Rene Higuita is still thrilling crowds in Colombia's second tier, where he turns out for Deportivo Rionegro.
Only time will tell when Higuita, Meola and their fellow gluttons for punishment will finally decide that enough is enough. In the meantime, football fans would be well advised to cherish these goalkeeping golden oldies; it may be some time before we see their like again.