Let’s say you’re writing a story that involves a character who’s smart, funny, gorgeous, and beloved by almost everyone.

They sound great, right?

Well, they might be. Or you might be inadvertently creating a “Mary Sue”.

So what’s a Mary Sue … and why should you avoid using one in your story?

Mary Sue Defined

A Mary Sue is a character who is way too good to be true. She’s often exceptionally talented for her age; love interests throw themselves at her feet; and she can pretty much get away with murder.

Mary Sue characters don’t have to be female, either. Male Mary Sues exist too (sometimes they’re called “Marty Sue” or “Gary Sue”, but most people just use “Mary Sue” to describe this type of character – whatever the gender).

The term “Mary Sue” comes from a 1973 piece of Star Trek fanfiction by Paula Smith that parodied this particular trend with a character called, you guessed it, Mary Sue.

There’s no one universally agreed-upon definition of a Mary Sue, but here are a couple that give you a good idea of what to look for:

[A Mary Sue] is what happens when a hero is too heroic—to pure, too powerful, too overwhelmingly good.

A Mary Sue is an over-idealized and seemingly-flawless fictional character, one often recognized as either a self-insertion character for the author, or a vessel for wish fulfillment.

These characters are often physically beautiful, exceptionally skilled, and universally admired—but only within the confines of the story.

(From The Problem with Perfect Characters: Mary Sues, Gary Stus, and Other Abominations, Jacob Mohr)

The most basic definition of “Mary Sue” is an original female character in fanfiction — which is largely about established characters and worlds — who is often close to perfect. Like, too perfect. Very good at her job, very desirable romantically or sexually, and sometimes very emotionally moving when she dies, tragically, and the other characters mourn her. The story usually centers around her, often warping established characterization in the process.

(From Mary Sue: From self-inserts to imagines, how young women write themselves into the narrative, Elizabeth Minkel)

Mary Sue characters can appear in almost any type of writing, including published novels and popular TV shows. (The often-criticised Wesley Crusher from Star Trek: The Next Generation is a frequently cited example, as is Bella Swan from the Twilight series.)

They’re particularly common, though, in fanfiction.

Here’s a quick litmus test to check whether your character is a Mary Sue:

If the answer to all these questions is “yes”, you very likely have a Mary Sue on your hands:

• Is the character an idealised version of you? (Be honest!)
• Are they popular with pretty much everyone?
• Are they a bit “too good to be true”?
• Do they have a surprising range of skills / expertise?
• Have they advanced a long way in their career despite being very young?

If the answer to all these questions is “no”, you very likely have a Mary Sue on your hands:

• Does the character have any real flaws? (“Clumsy” or “poor at math” are not flaws.)
• Do they ever fail at anything, in a significant way, in your story?
• Do they change in some way (for better or for worse) during the course of the story?

Common Confusions About Mary Sue Characters

Sometimes, people will call a character a “Mary Sue” based on a particular trait or aspect of the character.

These (common) things alone do not make a character a Mary Sue:

The character is a powerful female. You can (and should!) write strong female characters.  They only tip over into Mary Sue territory when they’re exceptionally skilled in multiple areas in an improbable or unexplained way. (E.g. if your character has been studying karate since she was five, it makes sense that she’s good at fighting – but if you never mention any type of training and have her effortlessly defeat three armed assassins, it’s going to seem ridiculous.)

The character has wacky coloured hair or eyes. While this can be a trait of a certain type of Mary Sue character, it’s also something you might well be using for other reasons – perhaps just because you like that hair / eye colour (which isn’t such a terrible reason to include it!), or perhaps because it has a particular plot relevance.

The character has multiple love interests. In certain stories, it’s normal and even expected for your main character to have more than one love interest. (Think of all the mainstream romance novels and films that involve – usually – a woman choosing between two men.) In some sub-genres, like reverse harem romances, the whole point of a story is about a character having several love interests at once. Even if the story isn’t a romance at all, it’s still perfectly plausible that a character might have more than one love interest.

They’re based on the author. While “Mary Sue” is sometimes seen as synonymous with “author insert”, it’s not necessarily the case that characters based on the author are Mary Sues. Some writers would argue that all their characters are based on them to some degree: after all, who else’s thoughts and feelings do we have direct access to? Just because a character shares some characteristics with the author doesn’t make them a Mary Sue.

They’re an original female character in a fanfiction story. Admittedly, this type of character has a fairly high chance of being a Mary Sue (compared with, say, original characters in original works). One of the main issues with this type of character is that they tend to steal the spotlight from the real main characters – the established ones who fans want to read about. But original female characters are not invariably Mary Sues.

The Big Problem with Mary Sue Characters

Mary Sue characters can be a lot of fun to write … after all, there wouldn’t be so many of them otherwise. If you’re purely writing for your own enjoyment, and you don’t plan to share your work with others, then indulge in as many Mary Sues as you like. There’s nothing wrong with a bit of wish fulfilment!

The problem comes when you want other people to read – and enjoy – your work. The sad truth about Mary Sues is that, for most readers, they’re boring and annoying.

You might think that readers would enjoy a story where someone smart, talented, good looking and universally loved saves the day again and again … after all, isn’t that a kind of wish fulfilment for the reader, too?

Some readers might indeed enjoy that. But what most readers actually want is a story where characters struggle, get things wrong, fail (at least temporarily), and change and grow. That makes for a satisfying, exciting story.

Mary Sue characters tend to “break” stories, too, either by the actual rules of the world being different around them (e.g. magic works differently for them) or by effortlessly winning everything — without it ever feeling deserved or earned.

Obviously, you can write what you want … but if you want your work to be read, avoid using Mary Sue characters.

Instead, make your characters real, complex people. Give them flaws (real ones that they need to overcome) and let them fail, before they succeed. Your story will be all the more satisfying for it.