A beautiful person and the niece of doctor strange in marvel lol

A beautiful girl and the niece of doctor strange from marvel lol and also a frickin BOWL! Not rlly but yes

It used to refer to a type of female character who is depicted as unrealistically lacking in flaws or weaknesses.
Now people use to refer to a "Female Character I Don't Like For Some Reason."

Rey from star wars

Captain Marvel. Nothing more. Just Captain Marvel

The type of character that is perfect in every way possible. Here's an example of a Mary Sue:
- Young, probably immortal
- Everyone loves them
- Always does everything without flaw
- Probably has magical powers
- Might be a hybrid (often crap like "half demon, half wolf, half princess, half human" because princesses are totally not human /s, and the character is probably written by an 8 year old that doesn't know about the term quarters)
- Has like 6 people after her
- Most likely female
- Only flaws are "clumsy" or something similar
Boom. There you have your very own Mary Sue/Gary Stue.

A Mary Sue is an idealized and seemingly perfect fictional character. Often, this character is recognized as an author insert or wish fulfillment. They can usually perform better at tasks than should be possible given the amount of training or experience. A male can also be referred to as a Marty Stu or Gary Stu, but Mary Sue is used more commonly.

While Mary Sue is too nebulous to be judged by any hard and fast standard, certain traits have become surprisingly popular in defining what "makes" a Sue. In an effort to make their characters more attractive without having to do the leg work of natural character development, the authors just add some of these superficial traits to their characters.