The Four Horsemen of the Infocalypse refers to those who use the Internet to facilitate crime or (pejoratively) to rhetorical approaches evoking such criminals.
The phrase is a play on Four Horsemen of the Apocalypse. There is not a universally agreed definition of who the Horsemen are. Terrorists, pedophiles/child molesters, organized crime like drug dealers, intellectual property pirates, and money launderers are cited commonly.
One of the most famous definitions is in The Cyphernomicon by the cypherpunk writer and engineer Tim May, which states:
8.3.4. "How will privacy and anonymity be attacked?" [...]
like so many other "computer hacker" items, as a tool for the "Four Horsemen": drug-dealers, money-launderers, terrorists, and pedophiles.17.5.7. "What limits on the Net are being proposed?" [...]
Newspapers are complaining about the Four Horsemen of the Infocalypse: terrorists, pedophiles, drug dealers, and money launderers
Digital rights activist Cory Doctorow frequently cites "software pirates, organized crime, child pornographers, and terrorists...