The Comprehensive Definition of "Mary Sue":
A Mary Sue is a character people place in their stories, usually by making her an exchange student from America. She is always idealized (beautiful, no faults, righteous) and meant to be modeled after the author. Often she is the daughter of Voldemort or Sirius and has special magical powers (wandless magic, animagi, veela, fire power, necromancy, premonitions). The readers are meant to love her, but they rarely do because she is ANNOYING and PERFECT. She is also the love interest of one or more main characters (usually if the author is in love with, say, Malfoy, Mary Sue would be too). Mary Sues usually have outrageous names like Quyntella Hope Izzabella Floweress Dragoncrest Loella Ellaella Rose Amonelliealla Belle Shadoweye Fireheart Zyzondellebella. Mary Sues are very common. I'd say they appear in 2 out of 5 full-length stories. Recently they've become less and less popular as people begin to differentiate between a Mary-Sue and a well-developed character. I hope that clears everything up! ~JuicyJuice
A Mary Sue is a character people place in their stories, usually by making her an exchange student from America. She is always idealized (beautiful, no faults, righteous) and meant to be modeled after the author. Often she is the daughter of Voldemort or Sirius and has special magical powers (wandless magic, animagi, veela, fire power, necromancy, premonitions). The readers are meant to love her, but they rarely do because she is ANNOYING and PERFECT. She is also the love interest of one or more main characters (usually if the author is in love with, say, Malfoy, Mary Sue would be too). Mary Sues usually have outrageous names like Quyntella Hope Izzabella Floweress Dragoncrest Loella Ellaella Rose Amonelliealla Belle Shadoweye Fireheart Zyzondellebella. Mary Sues are very common. I'd say they appear in 2 out of 5 full-length stories. Recently they've become less and less popular as people begin to differentiate between a Mary-Sue and a well-developed character. I hope that clears everything up! ~JuicyJuice