Apple never gave a reason why, but it was a very fitting name, seeing as Apple was far behind its competitors at the time and needed to cover a lot of ground very quickly, like a cheetah could.
And now, more than a decade later, Apple is sitting at the top, and again very fittingly, the next version in the line of OS X is named Mountain Lion.
All very nice metaphors, but what happens when they Animal Kingdom runs out of cats?
Mountain Lion will be the eighth version of OS X, which means Apple has already used more than a handful of cats.
After Cheetah came Puma, followed by Jaguar, Panther, Tiger, Leopard, Snow Leopard, and the current version, Lion.
But as Gizmodo points out, Apple has worked its way up in terms of cat ferociousness and all the best animals are gone.
So what kind of cat can Apple turn to next?
It could continue on with the slight name variations, like it did with "Snow Leopard" and "Mountain Lion," although its a bit of a cop out. If it did, it could go with a cat like the clouded leopard, but at that point, only zoologists will know what Apple is talking about.
Apple could also turn to the Lynx or Ocelot, but that's only if it doesn't mind sharing cats previously used for names by other tech products, in this case being Atari and Ubuntu. This might not be a problem actually, since Apple has been accused of taking the iPad and iCloud names from other companies in the past.
If its a fan of "Napoleon Dynamite," Apple could start naming its operating systems after cat mixes, like the liger or the tiguar. But just like Napoleon Dynamite, that probably would only be cool for about a month.
The last reasonable choice would be to take the retro route and use the sabre tooth tiger. Of course, that cat is no longer around, but have you seen how awesome they were?
The best bet may just be to move on to the next line of Apple operating systems and start fresh with a theme of luxury cars or types of birds.
But whatever you do, Apple, just don't turn to house cats. Please.