Diavolo

ディアボロ

Diavolo, the main villain of Part 5, was born in a female prison. His birth is a mystery because his mother claimed that he was conceived two years before her sentence and all the guards were female. Diavolo was raised by a priest in his mother's hometown of Sardinia because she can't raise him while in prison. When he turned 19, when the priest was constructing an apartment for Diavolo, he found his mother buried alive under a stone tablet. Around the same time, a fire broke out and the priest and Diavolo were among the seven who died in the fire. However, in reality Diavolo survived and joined Passione soon after. During that time, Diavolo recovered the bow and six Arrows in Egypt and quickly ran off with them. He then sold five of the Arrows to Enya Geil and kept the remaining one for himself (that same arrow was attached to Polpo's Black Sabbath). Between Stardust Crusaders and Golden Wind, he sets out to kill all his blood relatives, and those who discover his identity, to ensure his name is erased from existence and he took the pseudonym Soliddo Nazo during his years in Passione.
Diavolo means "devil" in Italian, fitting considering his personality and role as the main antagonist of Part 5.
Vinegar Doppio is Diavolo's young, innocent, and bizarre second personality. He considers himself as Diavolo's most trusted subordinate. Doppio acts as a disguise for Diavolo, when he interacts socially with others in the outside world. He turns into Diavolo whenever someone finds out about Diavolo's identity. Doppio communicates with Diavolo with an object that only Doppio hears ringing, making people think that he's insane, or scary (to what children think of him). Doppio usually makes the sound とぅるるるる~ (Turururu~), which is similar to a phone ringing. Doppio means "Double" in Italian, showing his nature as Diavolo's second personality.
Stand
King Crimson—A light red humanoid whose face appears to have a smaller copy of itself in its forehead, perhaps to mirror Diavolo's psyche. King Crimson has the power to predict up to ten seconds into the future, and "erase time," effectively causing a time skip, where everything except itself and Diavolo is suddenly changed to be in the state they would have been a short time later (usually 3–10 seconds later). Time still flows normally for Diavolo, who can interact (or not interact, he can choose which objects to interact with) with the time-skipped objects for the amount of time that would have normally intervened (to Diavolo this appears in the form of the would-have-been intervening objects' states being superimposed on each other, in a fashion akin to Nude Descending a Staircase). The nature of the time skip is such that, for example, he predicts a bullet coming at him, and erases the time that it would have hit him in. To the viewer a bullet that would have hit Diavolo will suddenly be shifted to be on his other side as where it would be seconds later.