A "good" Villain

What makes a good villain or maybe I should say a well-written villain? I see some villain characters on TV and in books where the story built them up to be an evil mastermind, only to have them caught by the simplest of means. Needless to say, it was very deflating to expect a dramatic end and get a pinprick instead.  The movie Law Abiding Citizen comes readily to mind, I was so disappointed when the ending finally played out. The mastermind villain the writers had built up was captured by the cheesiest of means - you can gather that I did not like it.  So, what does a well-written villain make? A character that is committed to their purpose and doesn't have a sudden attack of conscience. A character that is smart and clever, so that it is a challenge for the protagonist to catch him and rewarding when they do. And please, no cheesy endings that look like you just became tired of writing and decided to just end the story. A formidable villain that will challenge your protagonist, will not only give your story more dept, but will also give you a more satisfying ending. That is my goal in my mystery novels, to give you, the reader, a villain that they can love to hate (or not if you prefer) and be rewarded when he/she is caught.  
Until next time.....