All heroes and villains alike are obviously dynamic, meaning they go through minor to major changes in terms of personality traits, abilities, and lastly, morality. It is possible for any kind of hero to commit a FaceHeel Turn, meaning they have turned to the dark side through various causes, such as corruption, persuasion from other villains, etc. Whereas villains perform a HeelFace Turn, through other methods like purification, and again, persuasion from other heroes in order to win them over to the side of good. However, at least sometimes, a character will decide to join the side of neutrality instead, and because of that, the individual never joins sides, whether it would be factions, or various corporations alike through whatever reason may be.
Now granted, this is quite an unusual choice of action since it is quite rare for a malevolent as well as a benevolent character to join the forces of neutrality, even though neutrality usually avoids getting involved in conflicts and just wants to solve problems for the greater good, keeping things in balance, and as well as their utter capability to reform evil and pacifying good. Like all neutral characters, those that go through a Heel-Neutrality Turn, tend to be far more mature than ever, and they tend to focus on objectives of keeping everything in balance.
This trope mustn't be confused with the other trope, HeelFace Revolving Door, which is where a character is constantly dynamic whenever it comes to their own very morality, whereas those that commit a Heel-Neutrality Turn, will remain roughly in the middle despite the fact that they don't join sides. It's also not to be confused with Retired Monster, since it talks about characters that have retired from being villains, whereas Heel-Neutrality Turn talks about either villains and heroes deciding to join the forces of neutrality.
This is in contrast with Adopt the Dog (which simply means the neutral character does something good and joins the benevolent side), and Neutral No Longer (which means that the neutral character finally chooses a side). Compare with Team Switzerland, which is when a third party refuses to join either side of a conflict.
- During Black Moon Chronicles, at the end of the first series, Haazheel Thorn and Wismerhill are facing each other. Thorn's Dragon Greldinard remains on the sidelines, unwilling to participate in a battle he deems foolish (as both were allies up to then). After Wis succeeds, Greldinard shows up, asks if it was truly worth it and kneels, acknowledging him as his master.
- In DC Comics, Blackfire has turned from being a villain into a neutral character ever since she finally got what she wanted, which is becoming the ruler of Tamaran and its forces. In consequence of that, apart from becoming more cooperative, she became less antagonistic and she avoids taking sides during conflicts.
- One of Aesop's Fables is "The Dilemma of the Bat," about a bat that imposed neutrality upon himself to avoid making enemies. Briefly, war between the beasts of the earth and the birds of the sky seemed imminent. The beasts asked the bat to join their side, but the bat deferred, claiming to be a bird. Likewise, when the birds asked the bat to side with them, the bat claimed to be a beast. A last-minute truce between the lion and the eagle averted war, but left the bat with no allies and shunned as a distrusted pariah. "In seeking to make no enemies, I've succeeded in making no friends," the bat lamented.
- Enforced in The Witcher series by the witchers themselves. Their general mindset is to avoid getting involved into any conflicts between civilized species and only focus on eliminating monsters. Of course, given their Crapsack World, it is not always possible.
- Then again, this does not add up with the "good versus evil" idea; this world runs on Grey-and-Gray Morality, and there are rarely conflicts where one party is good and one is evil (excluding more-or-less good protagonists engaging against obvious villains).
- In Farscape, Crais, the Starter Villain, comes to the conclusion at the end of the first season that his pursuit of vengeance on Crichton was unjustified and insane, and spends the next two seasons as a Wild Card and later Token Evil Teammate, making it quite clear to everyone else that his sole priority is his own survival and that of his beloved Living Ship Talyn.
- In Shin Megami Tensei games where the Law and Chaos factions come into play, going Neutral is usually considered an option where humanity doesn't choose a side between the angelic Law forces and demonic Chaos forces.
- Knights of the Old Republic has Jolee Bindo, whose karma meter is permanently stuck in the Neutral line.
- In Steven Universe, after spending several millennia damaged and sealed in a mirror because she was in the wrong place at the wrong time, Lapis Lazuli prefers not to get involved with the Crystal Gems and their conflicts and only gradually comes to enjoy living on Earth. Her roommate Peridot, in contrast, embraces Earth after her Heel Face Turn and regularly assists and socializes with the Crystal Gems. As the threat of the Diamonds looms ever closer over the course of the story, rather than side with the Crystal Gems, Lapis flees Earth entirely to stay as far away from the crossfire as possible. With appropriate timing, she comes back, reasoning Homeworld will punish her like a Crystal Gem, so she may as well be one.
- In Transformers: Prime, Starscream tries to defect from the Decepticons to the Autobots, but Arcee tries to murder him by making it look like an escape attempt so instead Starscream decides to be a neutral player. Of course eventually he defects from neutrality back to the Decepticon forces to when being neutral ends up getting him nowhere and he realizes that unlike Megatron, he lacks the necessary resources to enforce any kind of rule over Cybertron.
- Futurama has The Neutral Planet, who has this as their hat.
"All I know is my gut says maybe"
- Star Wars: The Clone Wars: After being betrayed by Count Dooku and after the Nightsisters are killed, Asajj Ventress becomes a bounty hunter, working for both villains and heroes alike, including Obi Wan and Ashoka.