I hear people throw around the term "mary sue" far too often when critiquing characters but what exactly is a mary sue. Seriously I feel like this term gets tossed around far too much to the point the meaning of the word has become vague and muddled. It's gotten to a point where I feel certain characters in media are wrongly accused of being a mary sue or at least by my definition of the term. However due to how often this terms gets thrown around and how vague it is another person may define it completely differently. So I ask what's your definition of a mary sue?
This video pretty much sums up my thoughts on this subject: