Dhampir

Although the idea of vampires being sexy is generally associated with the Gothic Horror novels of the late 1800s, even before that, in the Balkan region of Europe, it was believed that some vampires would come back from the dead and have sex with their wives - sex that could lead to the birth of half human, half vampire offspring. Known various as Dhampyres, Dhampirs, Dhamphirs or Dhampyrs, these mythological beings were believed to have certain vampiric strengths, which made them excellent vampire hunters, but none of their vampiric weaknesses, such as an aversion to sunlight or need to feed on blood.

In /tg/, dhampyres are a comparatively rare sight; they're considered too much the natural fit for "edgelords" - the kinds of players who usually migrate to drow or tiefling PCs because they think the "dark, brooding, angsty character" is awesome - or else they're seen as too rooted in Gothic Horror. Others even think they're too fantastical to believe in their existence, even by the standards of your typical fantasy world. But, they do survive here and there.

Dungeons & Dragons

Dungeons & Dragons has had a couple of attempts at a dhampyre race, but none have really taken off officially; there was a "Katane" race in Dragon Magazine #313, and assorted "Half-Vampire" templates. Ironically, the closest time D&D got to it was in 4th edition; the Dhampyre as a feat-based "pseudo-template" was one of their earliest racial experiments in Dragon Magazine, whilst the Vyrkoloka of Heroes of Shadow was essentially a Dhampyre with its name taken from another kind of vampire.

The unofficial Ravenloft 5e corebook from the Fraternity of Shadows fansite features a dhampyre race as one of the options.

Pathfinder is the only "D&D edition" thus far to feature a fully supported dhampyre player race, with four sub-variants to reflect the four specific kinds of vampire present in Golarion.

Chronicles of Darkness

Dhampir in the original World of Darkness were introduced in the Time of Thin Blood sourcebook. Full-on kindred couldn't have kids at all. But "thin bloods," fourteenth or fifteenth generation vampires whose connection to Cain is extremely tenuous can, though the pregnancy is long and difficult because undead bodies aren't well suited to carrying kids.

The result is a dhampir, a creature mechanically all-but-identical to a revenant, or hereditary ghoul that produces its own vitae. Dhampir are living creatures, and have a pool of vitae separate from their normal blood, though they do get tired if they exhaust it. They suffer frenzy like a vampire, but can resist it much more easily, and like ghouls can go out in the day light and so on. Because thin-bloods have only started showing up in the last twenty or so years, no one knows what happens to an old dhampir.

Dhampyres were introduced to the New World of Darkness in the Vampire: The Requiem sourcebook Night Horrors: The Wicked Dead. Born of either blasphemous occult rituals or deep, sincere, obsessive love between a vampire and a mortal, dhampyres are cursed creatures who are hypnotically alluring to vampires, but whose blood is not only devoid of nutritional value for them, but exposes the vampire to a powerful curse if they share the same clan.

They're also mildly infamous for the fact that, because they're born of unnatural magical origins, they don't adhere to the standard rules of baby-making. So, you can get a dhampyre from a homosexual coupling, a female vampire could impregnate her male human lover, and a male vampire could fall pregnant by a female human lover, depending on what rituals are used to make the dhampyre in the first place.