Perhaps the greatest individual in the history of psychotherapy. I wish I could have met him when he was alive because his stuff makes a lot of sense. For those not in the know, he created Rational Emotive Behavioral Therapy.
I'm boiling it down very much so, but basically it says the individual is responsible for their own suffering. No one can "push your buttons", you do things of your own will. There are no "shoulds" in life, only "I would prefer to". You can find more about it here on wikipedia.
And now a little clip.