Someone who (usually falsely) claims victimization any time things don't go their way. Everywhere this person goes, they believe someone is taking advantages of them. This person has many many stories of The Man keeping them down, numerous abuse incidents throughout their childhood and adolescence and adulthood. This person will regale you with stories of their failures as a result of someone other than themselves. It's never their fault, in whole or in part. Life just isn't fair for these people.
The professional victim cannot take responsibility for his or her own shortcomings and life failures, so they claim to be a victim of circumstance and/or other people.
Did you fail a test? Were you reprimanded by your boss? Did your spouse or girlfriend or boyfriend leave your ass? Are you deep in credit card debt and have nothing to show for it? Well, claim victimization despite the facts and avoid ownership of the reality you helped create! Being a professional victim is great and once you start, you'll never stop - they never do! But be careful though - after about the 8th time you've been "victimized", you start to lose credibility and everyone wises up to you being a misery-loving freak. Or maybe you could just stop being a tool and stop blaming others for your miserable existence. But if you're a true professional victim, you won't.
A great example of a professional victim is Heather Mills.