Although an "Anti-Hero" once referred to one specific kind of character archetype, over time the term has evolved to cover several, many very different but all having one key aspect in common: serving as contrast to traditional hero types such as the Knight in Shining Armor, The Ace, and the Ideal Hero.
Type 1: The original anti-hero, this exists somewhat outside of the scale and thus does not have a set morality, but still tends to be good or neutral, with a few exceptions.
Type 2: These are more unambiguously morally good, and dispite being grumpy or snide they Are characters who cannot be corrupted by any means.
Type 3: These are iffier, but no worse than neutral. Some stay in the "good" category throughout. This type is willing to harm someone or otherwise do what they must do.
Type 4: These are the darkest possible while having fundamentally good intentions, but can also frequently be seen as neutral at best. Pay Evil unto Evil is the defining Trope here.
Type 5: These are a Darker and Edgier neutral at best, and recurrently A Lighter Shade of Black aimed against greater evils.Type 1:Classical Anti-Hero
This was actually the original understanding of the term, a character who is a protagonist but lacks the qualities of the hero as seen by the Greeks. He has a good heart but is a bit of Loser track record wise. He also have self-esteme issues. A Type 1 may transform into a full hero over the course of the story if they manage to overcome their inner demons, discover their courage or find their reason to fight.
. Unfazed Everyman
. any main character who is cowardly or ignorantType 2:Disney-Like Anti-Hero
This is arguably what the term often means in common speech—a character who contrasts with a squeaky clean Knight in Shining Armor. The term "Disney" is used, because giving it some thought, this character is actually pretty much a pure hero, with Heroic Spirit, except that they don't have the positive mental attitude that generally comes with being a straight hero. Like a Type 1, a Type 2 antihero stands a good chance of transforming into a straight hero over the course of the story once they confront their internal conflicts or fall in love with someone and devlope a desire to protect them.
.Knight in Sour Armor
.Hero with Vices Type 3: Dangerous Anti-Hero
While some of these share the snarkiness associated with a Type 2 Anti-Hero, they are somewhat darker than the previous version, as their Anti-Hero status is associated with their willingness to do good through "not nice" actions. This character can very easily be humorless while still being rather powerful. Essentially a meaner version of Type 2. Type 3 antiheroes may get nicer and turn into straight heroes over the course of the story, but they just as likely may not.
There is some division in this slot as to the acceptability of lethal force. Some will side against it, but others deem it a viable solution. In the latter case, it is generally a matter of last resort, but they will do what they have to do.
.Good guys who are a jearks to the coreType 4: Vicious Anti-Hero
This type of Anti-Hero will recurrently be extremely vicious. In some cases they might simply live in a very Ruined World setting, and could have been a "Disney Anti-Hero" in a more idyllic setting. There is some chance that a Type 4 may see the error in their ways, get rid of the cravings for violence, and change into a straight hero over the course of the story, but don't hold your breath; a more likely scenario is that they'll remain an Anti-Hero and retain many of their flaws, but shift up the scale to a more unambiguously good Type 3, or in rare cases type 2.
Note that there is also a separate flavour of this category, which trades the heroic objectives for somewhat nicer methods, or at least more redeeming qualities. Their objectives tend to be neutral to leaning somewhat unsavoury (but never outright evil), balanced by having lines they will not cross, soft spots for their friends and loved ones etc., as well as often being on the good guys' side, even if only by chance or because it turns the greatest profit.
Essentially, whereas the former flavour of Type 4 is more or less a more (too) extreme Type 3, this is a Type 5 with fewer vices and more virtues. That doesn't mean they can't become a Type 3, or even a Type 2, however, if they decide they like the good guys enough to join them whole-heartedly; however, it does mean that they're also prone to falling to a Type 5 if the good points start to lose out to their bad points.
. A troubled, brooding character whose passion causes A LOT of dramaType 5: Designated Hero
Far from Not a Villain, and range from being simply amoral characters who happen to be pointed at the villains for one reason or another, to being actively malevolent characters, only considered heroes because the villains they fight are much worse.
Ironically he's the lesser evil in a conflict.
. Sociopathic Heroes
. Unsympathetic Comedy Protagonist