My first test (and every test that I have seen, actually) work by counting up character features and counting up the ‘score.’ In the context of the great variety of stories and settings, this is not a very accurate measure. In this test, I will try something different, in hopes of producing a more accurate test.
The point of this test is to help people to look at their characters, and understand if there is a problem, something that needs to be worked on, not to make anyone feel bad about their characters. So no putting other people's characters through the test and then going 'ha-ha! Your character's a Mary-Sue!'
What makes a Sue a Sue(or a Stu a Stu) is that they are MORE than any other character: more beautiful, they get more attention, they are more skilled, more strong, etc.
So, is the character. . .
(if the character is more skilled in multiple areas, each of which has bearing on the plot, add an extra point for every additional skill)
A better fighter-
-than any other character?
Total up the number that applies to your character.
Subtract 1 if the character is shown to be less in some regard;
Subtract 2 if there is some circumstance making it serious: for example, if the character is very proud of some skill, but is shown to be less skilled than another character, subtract 2.
Compare the total to the ranks below:
0 - Definitely not a Mary-Sue
1 - Almost certainly not a Mary-Sue. It can be done, but it takes work.
2-3 - Borderline.
4 - You’ve probably got a problem.
5+ - Probably a Mary-Sue.