Shadar-kai

Ow the edge.

Even more edge.

Shadar-kai are a Dungeons & Dragons creature where you really have to specify what edition you're talking about. Both versions have a gothy sadomasochistic theme (Imagine a whole race of Cenobites from Hellraiser), but the difference between 3e and 4e really couldn't be much greater.

In 3rd Edition

An obscure beastie, the 3.5 shadar-kai is a species of Fae that has been dwelling on the Plane of Shadow for generations. This has caused them to suffer a magical affliction where they steadily fade away into nothingness, unless they can stimulate themselves. The most easy way to do this is via torture and self-mutilation, to the point that their iconic gear are arm-bands with cold iron spikes on the inside, which they drive into their own flesh to keep them "anchored" into reality. They hate all mortals for not having to put up with the same effect, blaming them for their choice to live in the Plane of Shadow in the first place.

In 4th Edition

They became a humanoid race and a playable species. Basically, they're the descendants of humans who migrated to the Shadowfell in pursuit of immortality. They got it... of a sort. If they can keep themselves active, amused and interested in life, they can live forever. If they succumb to ennui, they start fading out of existence. Their culture is thusly dedicated to stimulation in all sorts; carnal experimentation, sadomasochism, boasting contests, athletic contests... in essence, they're a race of "live for the moment" loudmouthed jocks, with a tendency to cut themselves when things get boring.

Ability Scores: +2 Dexterity; +2 Intelligence or +2 Wisdom

Size: Medium

Speed: 6 Squares

Vision: Low-light

Languages: Common, one language of choice

Skill Bonuses: +2 Acrobatics, +2 Stealth

Shadow Jaunt: Shadow Jaunt can be used as an encounter power

Shadow Origin: Considered a shadow creature for the purpose of effects that relate to creature origin

Winterkin: +1 racial bonus to Fortitude defense, +2 racial bonus to death/unconscious saving throws

In 5th Edition

Shadar-kai made an appearance for 5e in the November 2017 issue of Unearthed Arcana; whilst the focus was purely on crunch, their fluff was essentially a clumsy amalgamation of their lore from before - in a nutshell, taking all of their 4e lore, but making their base race be elf rather than human. As such, they are mechanically a subrace for elves, although their entire statblock is repeated here because 1d4chan is awesome like that.

+2 Dexterity, +1 Charisma

Medium

Speed 30 feet

Darkvision 60 feet

Keen Senses: Proficiency in Perception.

Fey Ancestry: Advantage on saves against being charmed, and immune to magic that puts you to sleep.

Trance: Trancing for 4 hours yields the same effect as an 8 hour sleep.

Deathly Cantrip: You know a single cantrip chosen from a list of Chill Touch, Spare the Dying and Thaumaturgy. This cantrip can't be changed at a later date. Your spellcasting ability score for this cantrip is Charisma.

Blessed By The Raven Queen: You can use a bonus action to teleport to an unoccupied space within 15 feet. After teleporting, you gain resistance to all damage until the end of your next turn, during which time you appear translucent and ghostly. After using this ability, you must complete a short rest or a long rest to use it again.

Shadar-kai later appeared in Mordenkainen's Tome of Foes but with some edits. Deathly Cantrip is removed but the range of their teleport is increased to 30 feet.