Too many companies have this Irreplacable Guy, let's call him Guru. He's been in the company for ages, knows all its history better than anyone else (politically as well as technically). Well, he should, for he's written some "core" components a decade ago and it's so damn smart that nobody has ever been able to understand it apart him. Well, nobody dares getting even close to it. Or just look at it. Even from very far away. When a problem occurs, people will do anything to avoid bothering Guru - he's so busy doing important stuff that they try to avoid disturbing him unless absolutely necessary. Even then, they put gloves on. Really thick ones. And Guru makes a lot of money - more than some of the VP's. Well he should - the company would collapse were he to squint at the windows of the company accross the street, even by accident. And Guru knows how important he is, and particularly - how irreplacable he is. The truth is, that deep inside, Guru is in tremendous stress - he knows that he's mostly bluff, and that all his "core knowledge" could be learned (with or without his help) in a few days. He even realizes that his skills have deteriorated over the years, for he never learned anything new in the last decade, nor done any serious work outside of his company. But he has no choice but to remain where he is, making sure the Irreplacable Myth remains as strong as ever and his job remains as secure as the Myth is strong.
In Hebrew we say: Graveyards are packed with irreplacable people.
Well it's true, in almost all cases, the Irreplacable Myth is exactly that - a Myth. It has been feeded by Guru himself, as well as the constantly changing staff, bad management and chance. I have personally been in both positions - an Irreplacable Guy and a Myth-Breaker. When I thought I was Irreplacable I used to joke that if I were to get run over by a truck, the company will crash. At some point I decided to leave the company - I hadn't been around enough time to become a real Myth. Yet my feeling of responsibility was so great that I told the company 3 months ahead of time that I was leaving (instead of the 1 month I was obliged by my contract). It took them a lot of time to find someone, so I had only a couple of weeks to pass everything to the new guy. And you know what? Everything went fine, the company didn't loose too much money and is still around today, making much more money than they did back then. On the other hand, I once started working for a company where there were not one, but two Irreplacable Guys. For various reasons (I must admit much of it had to do with me) they were both fired when the company had to cut down jobs, and not only didn't the company loose anything from it - many things went much better and faster, with a much better atmosphere after they left.
Are there real Myths? Well I think there are, but these are usually people not considered Irreplacable, so they become Myths only after they have left. These are usually very talented and creative people, who come up with ideas others would never be able to come up with. A real Myth is not one who knows a lot of stuff, he's one who creates things others wouldn't have thought of. That, ladies and gentlemen, is potentially an Irreplacable Guy!