You've probably heard of "superheroes" - crime fighters possessed of incredible powers, their identities masked behind colorful costumes. Justice-seekers such as Superman, Batman and the Green Hornet.

They're make-believe vigilantes - private citizens avenging evil deeds and subduing violent criminals.

In theaters, we cheer vigilantes such as Merry Olde England's legendary Robin Hood. And Paul Kersey, played by actor Charles Bronson, who walked the streets, avenging the murder of his wife and the attack on his daughter in five "Death Wish" movies.

istolethetv, Flickr Creative Commons
This is a Green Hornet lookalike, but the outfit is not atypical for true-life vigilantes who throw themselves into their roles.

Many Americans applauded the real-life "Subway Vigilante," Bernhard Goetz, who, in 1984, shot four men who assaulted him on a New York City subway train.

These days, all over the country, masked vigilantes are leaping out of the shadows to rescue potential victims of violent crime. The HBO cable-television documentary "Superheroes" followed 50 real-life crime fighters - including otherwise mild-mannered plumbers, teachers, and cashiers - who used weapons such as batons and stun guns to accost real and perceived lawbreakers.

One of latest citizen vigilantes is a 23-year-old Seattle man, Benjamin Fodor, who - wearing a black mask and matching full-body outfit and conveniently followed by a videographer - confronted a man who was menacing another person. "Phoenix Jones," as Fodor called his superhero persona, doused the aggressor with pepper spray - but later also sprayed some rowdy partygoers and was arrested for assault.

Indeed, law-enforcement agencies take a dim view of vigilantes. Few of them have combat or weapons training, the police say. The avengers sometimes assault innocent people. And they've been known to go overboard with their righteous zeal, beating citizens for littering or damaging cars whose drivers are thought to be speeding through school zones.

"If you want to dress up and walk around, knock yourself out," said Seattle police spokesman Mark Jamieson. "But inserting yourself into situations without knowing the facts is just not a smart thing to do."