For Mr Invisible, the first and last blow to his burgeoning career as a superhero was an unexpected punch that flattened his nose.

“After months of designing my costume, getting my street moves just right, it was my first week out as a Real Life Superhero – and probably my last. This tiny, tiny girl did not like me trying to calm down her screaming boyfriend. She blindsided me, I’m still bruised. It’s dangerous out there,” said the deflated would-be crime fighter last week.

Mr Invisible is cheered that at least his grey one-piece “invisibility suit” works, proven when a drunk urinated on him in an alley. But he is weary of lurking in dark, down-town Los Angeles after dark.

The 29-year-old graduate is “refocusing” on his day job as an insurance salesman. His farewell appearance will be at a New Year’s Eve party.

Mr Invisible may be living up to his name but his spray-painted “supershoes” will quickly be filled by another Real Life Superhero eager to save America from itself. There are, according to the recently launched World Superhero Registry, more than 200 men and a few women who are willing to dress up as comic book heroes and patrol the urban streets in search of, if not super-villains, then pickpockets and bullies.

They may look wacky, but the superhero community was born in the embers of the 9/11 terrorist attacks when ordinary people wanted to do something short of enlisting. They were boosted by a glut of Hollywood superhero movies.

In recent weeks, prompted by heady buzz words such as “active citizenry” during the Barack Obama campaign, the pace of enrolment has speeded up. Up to 20 new “Reals”, as they call themselves, have materialised in the past month.

The Real rules are simple. They must stand for unambiguous and unsponsored good. They must create their own Spandex and rubber costumes without infringing Marvel or DC Comics copyrights, but match them with exotic names – Green Scorpion in Arizona, Terrifica in New York, Mr Xtreme in San Diego and Mr Silent in Indianapolis.

They must shun guns or knives to avoid being arrested as vigilantes, even if their nemeses may be armed. Their best weapon is not muscle but the internet – an essential tool in their war on crime is a homepage stating the message of doom for super-villains.

This is more than bravado, say veterans. It may help as evidence after a Real has been arrested or even committed to a mental health hospital for evaluation. That happened to Mr Invisible’s equally short-lived predecessor, Black Owl, who last summer had to be sprung from a psychiatric ward by his teenage daughter who told doctors: “Dad forgot for a moment, when faced with police, just for a moment, that he did not have real superpowers. He could not just fly away.”

“This is a more serious business than it looks,” said Citizen Prime, whose $4,000 (£2,700) costume disguises an Arizona businessman and father of a toddler who thinks his cape, mask and stun-gun are cool.

Prime patrols some of the most dangerous streets in Phoenix but, like most Reals, is reluctant to speak about the villains he has dispatched with a blow from his martial arts-honed forearm. He does admit helping a motorist change a flat tyre.

“Kids love the costume, so I seek to keep them out of the gangs today rather than take them on tomorrow,” said Prime who, at 41, regards himself as on the mature wing of the Real community.

He is worried about lunatics and hotheads. He says he would never act like the Black Monday Society in Salt Lake City who interrupt drug deals in public parks and face off against armed thugs.

Utah police officers say they appreciate Ghost, a 33-year-old concrete worker, and his colourfully costumed cohorts Insignis, Oni, Ha! and Silver Dragon. But other police departments recall that America’s most feared gangs, the Crips and the Bloods, were also born as idealistic “community defenders”.

It can be dangerous. Master Legend of Florida, who arms himself with a pepper-spraying cannon powered by cans of antiperspirant, was attacked by a man with a hammer.

There is a high burn-out rate. Terrifica, a 5ft 9in redcaped superheroine, who would manhandle drunken girls away from heavy-handed dates in nocturnal New York, spoke about how she despised her “weak, needy and dumped” alter-ego Sarah.

Artemis of San Diego reported on his blog that he had heard a woman screaming outside his home but by the time he had dressed up in his costume the police were already there. Kevlex, 47, who runs the Superhero Registry, says he patrols more in winter than summer in Arizona, when his Kevlar and Spandex kit itches. But the deadliest kryptonite against a superhero is boredom.

“I was out every night, 8pm until 2am, hanging about all the bad corners and nothing happened, nada, zip,” recalled Mr Invisible. “It was raining: even the drug dealers were at home. And often cops are just too good at their jobs.”

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