He was one of the most popular heroes of the past century - the star of film, television, radio, novels and most of all, comic books. Writer Harlan Ellison once suggested that he was one of five fictitious characters known to every man, woman and child on the planet (along with Robin Hood, Sherlock Holmes, Tarzan and Mickey Mouse). But when Superman died last year, hardly anyone seemed to care.

The Superman who died saving the universe was the same Superman who debuted in the first issue of Action Comics in 1938. Naturally, this would make him well past retirement age. Indeed, publisher DC Comics had long explained the agelessness of their super-heroes by revealing that their original heroes (who flourished during World War II) all came from a different universe to the contemporary models. When the younger heroes crossed universes, they would find themselves meeting older, semi-retired versions of themselves.

The original, now-deceased Superman was perhaps the greatest of them all. His sales were more consistently high (in the days before every kid had the internet, an XBox, or even a television set), and he started the legend. But he was already old in 1985, when DC decided that he and his wife, Lois Lane, should retire to a place of no return.

All would have been fine - except that 20 years later, DC decided that he should return anyway, in a series called Infinite Crisis. In this ultra-violent series, in which several DC heroes and villains suffered hideous deaths, the first Superman died heroically... and comic-book fans didn't seem to care.

Why did a hero of this calibre attract such a muted reaction upon his demise? Partly because super-heroes die all the time - and often, they return. The current Superman, for example, was pummelled to death by an alien psychopath in 1992. If this was meant to be a sales gimmick... well, it worked like a charm. The resulting story, "The Death of Superman", broke comic-book sales records. Within months, however, Superman had been resurrected by Kryptonian technology. Nobody really thought he was dead.

Anyone who watches soap operas might be aware that characters often return to life in various creative ways. In the fantasy world of super-heroes, however, writers can be even more imaginative. In the past, we have discovered that heroes (and villains) have not died as assumed, but had been replaced by androids, clone or cosmic beings. It has been revealed that they had a secret super-power that restored their life, or that they teleported away just in time. In some cases, history has changed, meaning that their death never even happened!

Of course, other heroes simply wouldn't be allowed to die. Nightwing, co-star of the animated series Teen Titans, was also supposed to die in Infinite Crisis - until DC's editors stepped in to save him. Killing off a 95-year-old, long-retired hero is one thing, but killing a young TV hero