AlbertEllis revolutionized psychotherapy by proposing that people didn't have to be helpless victims of their pasts and that endlessly going over their life with a Freudian Analyst could do more harm than good. He founded cognitive behavior therapy, the principles of which helped me dig my way out of depression, and so he is in no small part responsible for saving my life, or at least my sanity, even though I first learned of his ideas via a book written by one of his students.
Every profession needs someone who is willing to barbecue sacred cows and speak his mind and he filled the role well. He even recently filed suite against the BOD of his own institute.
93 is a good run and he was active up to the end with a newly finished book that will be published posthumously.