Hades Shaded

Purgatory has a flame, and it has scorched the skin of this character. This usually is depicted as an even tan across the entire body (there are no tan lines). Note, this person doesn't have to be evil per se, but they will have a grim origin or power source.

Can have Unfortunate Implications; so sometimes instead of being "black" or "brown", they're sometimes other spectrums of darker colors.

Do not confuse with someone who is merely sporty or blue-collar; such as the Dark-Skinned Redhead, that is just the effect of natural sunshine and outdoor work. The Dark-Skinned Blond tends to be an exotic racial characteristic. Contrast Undeathly Pallor.

Anime and Manga

 * Sailor Pluto from Sailor Moon; while she's the soldier of time, not necessarily a bad power in itself, she is a Well-Intentioned Extremist in one arc, she gives off a mysterious and wise aura and is suspected to be thousands of years old, and her powers have a lot of forbidden aspects that could tear the timeline apart. Thank goodness for Stable Time Loops. It's also notable that a common theory based upon one line in the manga suggests that she's a demigoddess.
 * Archer from Fate Stay Night. Especially noticable in that
 * For that matter, "Black Ilya" aka Kuro from Fate Kaleid Liner Prisma Ilya.
 * Akio (and Anthy) from Revolutionary Girl Utena.
 * Urd from Ah! My Goddess, and her mother Hild; the Queen of Nifleheim.
 * Angol Moa from Keroro Gunsou.
 * Rudger Godwin, following his death and rebirth as a Dark Signer.

Literature

 * Depictions of the Devil in the 19th century often described him as a figure all in black; including swarthy skin, as if blackened by soot; Nathaniel Hawthorne's "Young Goodman Brown" is a good example.

Mythology

 * Hades, aka Pluto, god of the Underworld, was often described as dark-skinned.
 * Satan, in typical Fire and Brimstone Hell Big Red Devil depictions, has red skin from the fire below.
 * So it's not so much that he's naturally red as it is he is sunburned? That's...a lot less badass.

Video Games

 * Akuma of Street Fighter.
 * Ansem/Xehanort from Kingdom Hearts
 * Carona aka "Another Marona" from Phantom Brave.
 * Rozalin from Disgaea 2 Cursed Memories takes on this characteristic when.
 * Princess Sapphire in Disgaea 3 Absence of Justice.
 * And now Fenrich from Disgaea 4: A Promise Unforgotten.

Web Comics

 * Zimmy from Gunnerkrigg Court has a strange ashy grey skin color in addition to her eyes covered in black gunk and More Teeth Than the Osmond Family. It's unclear whether this is supposed to be an unnatural feature in-universe, as it's not that far from a few other characters' skin tones.
 * Rose from Homestuck turns grey when she

Western Animation

 * Raven's demonic parentage from Teen Titans makes her blue-ish gray.
 * Dr. Drakken from Kim Possible is blue. We're not entirely sure why; but it's related to his being evil; apparently, as Ron Stoppable turned evil one episode and also turned blue. Okay, he's not nearly as Badass as the rest of these examples; but that's what evil is in the Kim Possible universe.
 * Not really. Ron got Drakken's specific brand of evil in that episode(via a literal Plot Device), and none of the other villains are blue, so it's a complete anomaly. Shego's green, but she has an actual backstory regarding that.
 * Oleander, Villainous Glutton on Sushi Pack, has lavender-shaded skin for no explained reason.
 * Hades in Disney's Hercules has pale ashen skin, but on the episode where he steals the sun, he develops a tan worthy of George Hamilton.

Tabletop Games

 * The Drow or Dark Elves from Dungeons and Dragons are dark-skinned; sometimes blue to avoid the Unfortunate Implications.