Essential classical repertoire

[brriker]

I was just curious as to what people think is essential repertoire for a classical pianist?  Of course, I know that personal taste, ability, etc. makes a difference here and this is all subjective.  What do you think is music every pianist should know?

Personally, I would say all the Chopin etudes, Bach WTC, and Beethoven sonatas.  I know this is a pretty standard answer.