King Crimson

King Crimson (キング·クリムゾン) is the Stand of Diavolo, featured in Part V: Vento Aureo. It has a sub-Stand, Epitaph (エピタフ), which is primarily utilized by Doppio. Speaking in both ability and strength-wise, King Crimson may be one of the strongest Stands in existence, being limited only by physical attack range and Diavolo's own personality.

Appearance
King Crimson is a humanoid Stand of a height and build similar to Diavolo's, but tends to look much bigger and taller. Its body is covered by a raised diagonal grid, red underneath; save for its face, neck, shoulder guards, elbows, hands, abdomen, crotch, knees and feet/footwear. Its eyes comprise sharp orifices of a steep inward slant; from which emerge small, round fishlike/amphibian/reptilian eyes. It constantly bares its teeth through a small mouth. Its crown is flat; and from its forehead emerges two raised levels, the front of which bears a smaller, oval face of the same expression. Epitaph is the pink-colored second face on King Crimson's forehead, duplicated in its same position on either Doppio's forehead. It creates images on the inside of its user's hair, and as such whenever active Doppio's bangs or Diavolo's hair is pulled forward and float, allowing the user to look in.

Its design is inspired by the character George, from the 1990 science fiction film Total Recall, who had a second face on his chest.

King Crimson
Erasing Time: King Crimson's signature ability is, to put it simply, skip time. To go into detail, it creates a space that deletes anywhere from .5 to 10 seconds worth of time with only Diavolo being able to maneuver in this realm of missing time, leaving only the results of actions that would've normally occurred. Unlike The World, things do happen during this time frame - someone ascending a staircase, food being eaten, books being read - it's just no one can remember and thus it feels as if time has skipped (though, most people don't perceive this fact) because the results of the actions have already occurred: you've reached the top step, you've finished your meal, you're several more pages into the book than you were before. And, to people outside of the pocket of time, Diavolo appears to be teleporting.

The primary use of the ability seems to be limited to mobility (readying a position from which to attack, creating sneak attacks, "teleporting") and defense (skipping the impact of attacks, thus preventing wounds) as Diavolo is never seen attacking during this pocket of missing time. This allows Diavolo to dodge things that could otherwise wound or kill him, such as Aerosmith's bullets or a fist, which can often continue on as if he wasn't standing there at all. King Crimson also has mundane uses that Diavolo exploits to preserve his identity, ranging from a fast clean-up of a heavily littered room to simple scare tactics. It's never explained in the manga proper if Diavolo can attack during this time-frame, as the most on the offensive side he's done is carry someone and splash blood in another's face.

The world of erase time changes from medium to medium; in the manga, the world is displayed with objects badly superimposed over their current self in all ways that they could move during the time frame, in a fashion akin to Nude Descending a Staircase, and at times the environment tears itself apart into a void filled with debris. In his first game, it simply slows opponents down, while in his second game appearance the time-stalled world is largely red with a desolate cracked ground and enemies cannot move an inch until he attacks (which automatically breaks the spell).

There are three key weaknesses to King Crimson, but Diavolo has had his Stand long enough to understand ways to get around them. The first is that its physical attack range is only slightly longer than Diavolo's, but due to its ability this isn't often a problem. The second is that Diavolo could easily be found out if the fight is not one-on-one due to there being multiple people to keep track of; Diavolo, as such, opts only for one-on-one fights and, if forced, will begin using sneak attacks and the element of surprise. Finally, the third is that King Crimson's ability duration is dependent on Diavolo's stamina, as during the battle with Risotto Nero, he admitted that the iron-deficient and tired state he was currently in prevented him from stopping time for more than an instant; as such, he tends or tries to make his fights short.

Super Strength: King Crimson is one of the strongest Stands, rivaling Star Platinum, The World, and Crazy Diamond. King Crimson was shown to have killed several people just by punching them right through their abdomen with one blow, rather than the standard chain punch all other Stands use, and above that it seemed that a tremendous amount of endurance was needed just to take one hit from King Crimson without the person suffering a tremendous injury; even Giorno lost his entire arm due to the power of a single strike. This is further shown by Leone Abbacchio and Jean Pierre Polnareff dying within seconds/panels of being hit.

Faster-Than-Light Speed: King Crimson has shown to be able to easily parry, react, and even outmaneuver faster-than-light Stands like Silver Chariot, Sticky Fingers, and Gold Experience, even without the use of Epitaph. King Crimson's speed may even be comparable to that of Star Platinum.

Epitaph
Prediction: From up to ten seconds, Epitaph gives Diavolo and Doppio the ability to see into the future through creating images on the inside of their bangs. The image produced includes the general area with Doppio/Diavolo as the main focus, allowing either of them to see what happens around them as well as directly at them. The prediction of the next ten seconds, according to Diavolo, cannot be avoided but can have steps taken to steer it in a new direction - such as when Doppio realized a pair of scissors would form inside his throat, he easily tore them out in order to save himself.

Doppio is the only one generally given Epitaph, but Diavolo is aware of how to use it and how long it lasts. It's unknown if Doppio can summon it himself or whether it's limited by Diavolo's permission. Doppio can also use King Crimson's arms as his own, primarily the right arm. The sub-stand is entirely defense and reaction-based, and it can be assumed that it's how Diavolo uses it to predict how his opponents move and thus how to attack them accordingly. So far, only the ability of Gold Experience Requiem has been shown to bypass Epitaph and it does not seem to be affected by its user's stamina.

Trivia

 * In the western release of All Star Battle, King Crimson is renamed as "Emperor Crimson", while Epitaph is renamed to "Eulogy".  The first one is likely intended to be a pun due to Diavolo's statements that he "will be emperor ", while an epitaph is an encarving on a gravestone and a eulogy is a speech delivered at a funeral.
 * Much like Dio's "Time is frozen"/"And time resumes", Diavolo has his own phrases to go along with King Crimson's abilities: "Time has been erased" for when he activates the ability and "Time goes on again" for when he deactivates it.
 * In an odd choice for art, King Crimson is often replacing Diavolo through a similar function: prior to Diavolo's face being shown, during several moments of skipped time, and during the Silver Chariot Requiem battle, it is King Crimson shown emoting and speaking instead of Diavolo himself.  This is not to be confused for sentience, however.
 * While it's likely this way in order to hide Diavolo's appearance up until his full reveal, a fan theory suggests that King Crimson is a rogue Stand, similar to Anubis, that had possessed Doppio and puppeteers him.  This is also used in the novel Jorge Joestar, where one of the alternate universe Giornos was possessed by King Crimson near the end of Vento Aureo, leading to the split Doppio becoming his own person.
 * Due to the paradoxical nature of King Crimson, combined with a poor English translation of Vento Aureo being around far longer than a high quality translation and the fact that explaining the ability can take anywhere between one sentence to an essay, saying "It just works" is the most common answer to how King Crimson works in the American fandom.  Noticably, the two games Diavolo are in have different interpretations:
 * In GioGio no Kimyō na Bōken: Ōgon no Kaze, the time erase was shown to slow down the opponent's actions while Diavolo still moves at normal speed for the duration of the obliterated time, a mechanism similar to Made in Heaven's time acceleration abilities.
 * In All-Star Battle, it acts similar to The World - through a counter, Diavolo creates a skipped time space in which he is free to move about and the opponent is frozen in space, but by attacking the opponent, the spell is broken.  King Crimson also acts as his dash and Epitaph can be activated to allow Diavolo instant dodging without taking out his guard meter.
 * However, interesting glitches were found in ASB involving King Crimson's counter and Epitaph, turing the "It just works" reply in a bigger joke than before.  If Diavolo activates the King Crimson time-skip counter while he's hit with a projectile, followed by the opponent activating a HHA or a GHA, there are interesting results.  There is also a glitch involving using his HHA and then dashing through the opponent, resulting in Diavolo becoming invisible.  And, prior to a patch, this was possible.
 * Physically, King Crimson is possibly one of the strongest Stands in existence. Unlike Stands like Star Platinum, it normally attacks not with a sequence of punches, but rather with a single attack. This is backed up by how Abbachio and Polnareff, when struck once through the body, both died within seconds/a few panels whereas Kakyoin, who suffered a similar wound, lived on for several pages.
 * Due to being hit by Gold Experience Requiem, Diavolo effectively had his Stand destroyed as the final attack removed all of Diavolo's "willpower", which is what powers the Stands.