Oscar Wilde - because I reckon he'd be awesome to party with
The Marquis de Sade - I just think it'd be interesting to meet him.
Milan Kundera - he's one of my all time favourite authors and The Unbearable Lightness of Being is quite possibly my favourite book.
I don't know if I'd like to actually go to the party as myself, because I don't know that I'd be able to contribute to it on their level. But I'd like to hear their ideas. I'd be a fly on the wall at their party.