"Before studying Zen, cats are cats and mice are mice.

While studying Zen, things become confused.

After studying Zen, cats are cats and mice are ignited explosives."

I want your head at any price.

The trinitrotoluene bodhisattva is quietly waiting for you behind this the corner.

Master! I am sorry for sitting on your litter box.

Meow Meow Meow? Mrow Mrrroooow Meow Meow Mu Mu Mu Mrrow?

Umm...and now for something not completely different: A Kierkegaard on a pogo stick.*

*Pictured not leaping.

Where's Edmund Husserl? You seriously need Husserl's question of consciousness. Consciousness is intentional or every consciousness is consciousness *of* something. He formalized an alternative to Descartes cogito and the objectivistic thinking of the empiricists.

If you'd like to throw some more of the explicitly phenomenological thinkers like Heidegger and the existentialists like Camus, don't forget the questions that lead up to them. Then of course, we'd have to add the other Pre-Socratics, the Stoics, St. Augustine, Aquinas, John Locke, and so on...

At least Immanuel Kant would've been there. That naughty Prussian created more problems than anyone would care to name. :D (Well maybe with the exception of Mr. Plato.)

The worst thing you can do is come up with a list of most important philosophers because the other philosophers can't agree with whom to add!

And I second Michiel's request to add Hume.