Ha Ha Ha

What has NO lips, white skin and green hair?
A Joker.
I'm sorry about that

But yeah anyway so the Joker is classified as one of the greatest comic villains ever, however there has not been an amazing adaptation on television or cinema, however In the animated series he has been well portrayed.
So in the 60's TV series they had Cesar Romero:

Cesar Romero: Still had a moustache

In the movies he was portrayed by Jack Nicholson

And Heath Ledger:

In the animated series (as well as Arkham Asylum and in Arkham City) He was voiced by Mark Hamill

Personally I have no care for the Heath Ledger adaptation for the reason that it is mostly different to the comics. The Joker was formed through falling in a vat of chemicals and had his lips burned of, hence the smile, Heath Ledger's adaptation was formed through Self-mutilation and child abuse. Most notably the Glasgow smile he donned. He doesn't have the humour of the original Joker (such as the way he kills people) and he is just a psychopath.
Personally I feel that the Heath Ledger is overhyped and is not as good as people say he is. He is alright.