We don't know his real name and word is he lives in hiding in Budapest. Yet in a world where information is power, the man who calls himself "John" seemingly has unfettered access to things that are supposed to be private and confidential.
And he's not afraid to use that information.
It began nearly two years ago, when "John's" Football Leaks website began uploading original player contracts, transfer agreements and assorted other football-related documents. A host of big names would eventually see their private dealings published online, from Gareth Bale to James Rodriguez, from Antony Martial to Paul Pogba, from Neymar to Cristiano Ronaldo.
The impact was virtually immediate. Twente, Dutch champions in 2010, were banned from Europe for three years after Football Leaks revealed that they had improperly accepted money from Doyen Sports, an image rights company which was also involved in the now banned practice of Third Party Investment (TPI) -- AKA Third Party Ownership (TPO).
Doyen claimed Football Leaks had hacked their servers and attempted to extort money from them. An ongoing criminal investigation was launched in what is believed to be "John's" native Portugal. The Football Leaks site itself jumped from server to server, eventually going dark.
The investigation is ongoing. John revealed he's Portuguese in an interview with Der Spiegel.
In December 2016, however, "John" and Football Leaks resurfaced, this time in collaboration with a number of mainstream European media outlets. "John" shared a total of 1.9 terabytes of data, roughly the equivalent of half a million bibles.
This time, Football Leaks documents contributed to investigations by Spanish tax authorities into Ronaldo and Jose Mourinho while, in France, the financial prosecutor's office opened a preliminary inquiry into money-laundering and tax fraud.
"John" himself claims his aim isn't extortion. In the Spiegel interview, he says he is simply a football fan who is concerned by the lack of transparency in the transfer market, which lends itself to corruption, money laundering and, as he puts it, "individuals unfairly enriching themselves through football." He describes whistleblowers likes Julian Assange and Edward Snowden as a "big inspiration" to him and his group.
Equally, "John" says the documents aren't the result of hacking, but rather people in the game freely passing on information to him and his group. Doyen and others dispute this claim and, indeed, given the sheer breadth of information he has leaked it seems extraordinary that a handful of people in Portugal could have access to so many original documents.
Whatever the case -- whether "John" and his group are hackers themselves, whether they receive documents from hackers or whether a wide range of people freely pass them documents -- clubs, players and agents around Europe are spooked. It's not just the potential, in some cases, for unethical or even criminal activity, or the fact that many view keeping private information private as an essential part of maintaining their competitive advantage over rivals. It's the mere fact that someone appears to have access to the most privileged information in the game and the authorities can't stop him and all of a sudden you're in an episode of "Mister Robot".
Inevitably, all they can do is invest more in cybersecurity. Gag orders against the media can only go so far. A Spanish Court, following complaints by a law firm representing unnamed clients, issued an injunction against outlets in the EIC consortium from publishing further "Football Leaks" documents but, for now, this only applies in Spain. And, in any case, in the age of the internet, it's virtually impossible to enforce.
"John" and his crew are holding many powerful people's feet to the fire. The scary part is nobody knows who is behind them and what they are planning to do next. If "John'" not a hacker, he could be a stooge being used by hackers. Either way, the fact is Football Leaks can break in and out of club and agency servers. If they can do it to them, they can do it to anyone.
Of course, if football made its business more transparent in the first place, which would be a smart course of action, there would be virtually no reason for "John" and Football Leaks to exist in the first place.