Talk:Earth ponies/@comment-76.173.83.63-20120829234933/@comment-3106212-20121014010406

I hate to do this to you, but Tv tropes probably has the best explanation: http://tvtropes.org/pmwiki/pmwiki.php/Main/MarySue

Its something that is easier to recognize than define, but it generally refers to a character an author paints as unrealistically perfect or glaringly overpowered.