By Alex Webb BBC News Online entertainment staff

The box office success of the Spider-Man film is a sign, were it needed, of the enduring appeal of the comic book superheroes.

In an age when the lack of real-life heroes is often lamented, the success of Spider-Man shows that even these cynical times hunger for a hero - and an invented one will do.

The superheroes who have zoomed onto cinemas screens in recent years are almost all from the great period of US comic book invention between the wars.

Superman first appeared in 1939

The great crash of 1929 is sometimes seen as the trigger for the flowering of fantasy characters in cheap US comic books, which provided a glimpse of a world where right always won in the end.

Alex Raymond's Flash Gordon, Chester Gould's Dick Tracy and Hal Foster's adaptation of ER Borroughs' Tarzan were among the earliest heroes of the genre - and all have been adapted for film.

The first of the "costumed" characters was The Phantom, created by Lee Falk and Ray Moor.

But perhaps the greatest of them all was Superman, who made his debut in the first issue of Action Comics.

Popular memory

His creators, Jerry Siegel and Joe Shuster, sold the rights of Superman to DC Comics in the 1940s, and missed out on the commercial exploitation of one of the most famous fictional characters ever invented.

Sensing the money to be made out of satisfying superhero hunger, US comic artists created literally hundreds of new characters, of whom only a few have survived in popular memory.

Val Kilmer played the caped crusader in Batman Forever

One who certainly has is Batman, created in 1939 by Bob Kane - a darker and more menacing character than Superman, but one who also shares the complexities of a double-life.

Timely Comics, which would later become Marvel Comics, introduced The Human Torch in the same year.

This was followed by Pep Comics' The Shield, G-Man Extraordinary and then by Whiz Comics' Captain Marvel.

And in a burst of patriotism shortly before the US entered WWII, Timely Comics invented Captain America.

Secret identity

The 1960s saw a resurgence of interest in US comic culture, partly fuelled by the decade's counterculture which itself inspired a new generation of comics.

Marvel Comics created the Fantastic Four, Silver Surfer, Thor, Hulk and X-Men, as well as one of the great superheroes, Spider-Man - the secret identity of frail and shy teenager Peter Parker.

Spider-Man, like Superman, leads a double lilfe

Marvel Enterprises has already announced that there will be a sequel to Spider-Man, to be released in 2004 - with a third film planned for two years later.

And Marvel characters will be appearing in a further four films next year alone, starting with Daredevil in January from 20th Century Fox.

It will be followed by an X-Men sequel in May, The Hulk in June and Punisher, about a vigilante ex-cop, two months later.

The Hulk will be directed by the acclaimed filmmaker Ang Lee and will star Eric Bana, alongside Oscar winner Jennifer Connelly.

Warner Bros, which owns DC Comics, is also working its own stable of superheroes.

The studio is promising two new Batman movies, a new Superman film, a team-up between Superman and Batman, a Wonder Woman film - and a Catwoman film.

The studios clearly expect the superhero goose to continue laying golden eggs.

X-Men: The sequel arrives in May 2003

The first Superman, starring Christopher Reeve, earned more than $134 million (�91m) on its 1978 release - a huge total at the time.

Warner's original Batman film in 1989 made $40.5m (�28m) in its first weekend alone, before bringing in more than $251m (�171m) in the US.

And X-Men broke records in July 2000, earning $57.5m (�39m) in its first three days.

But these figures have been dwarfed by Columbia's success with Spider-Man, which earned $114m (�78m) in its first three days - more than doubling the studio's previous best opening, Men In Black.

All of this suggests that superheroes will continue to delight the studios with superhuman feats at the box office for some time yet.