Counter-Terrorists are characters specially trained or devoted to preventing terrorist activities and hunting down known terrorists either to capture in order to bring to justice or eliminating with lethal force if they are deemed too dangerous to be kept alive - most are highly skilled law enforcement, military or similar but others have origins as freedom-fighters or similar and are forced into the role either via personal tragedy or a desire to rid the world of dangerous criminals.

Due to its very nature counter-terrorism overlaps heavily with law-enforcement and peacekeeping, if a counter-terrorist is not authorized they are, obviously, also a type of vigilante (also unauthorized counter-terrorists, unless working in a lawless or post-apocalyptic society, are by definition hypocritical as they would be employing terrorist tactics, albeit usually with focus on preventing civilian casualties (though the most extreme versions of these vigilantes may be willing to harm civilians for a "greater good".

Many superheroes will also be a form of counter-terrorist due to the extreme conditions they fight in and the often extremely destructive opponents they face on a regular basis.

They are, as the name implies, the heroic foil of Terrorists.