The Penanggalan is a vampire-like monster from the mythology of Southeast Asia, and is similar in many ways to the Aswang. These cursed women look like normal people during the day, but at night their head detaches and flies off, dragging its lungs, heart, stomach and intestines beneath it as it flies around in search of blood to drink, with a particular fondness for feeding on pregnant women and young children (another Aswang-like trait). They can be detected during the day by a persistent odor of vinegar, as the head needs to soak its organs in vinegar to shrivel them up sufficiently in order to reinsert them back into its body. Because they must reunite with their body before sunrise, as sunlight will kill them if it touches them in their true state, traditional methods of warding them away involve creating barriers of thorns or broken glass, as the Penanggalan will not approach these for fear of getting tangled up in them. Destroying the body, or filling it with thorns and/or broken glass, is the best way to ensure they will die at sunrise.
In the Old World of DarknessEdit
The Penanggalan is not a specific type of monster, and is instead a title given to a female Kuei-jin of the Golden Courts who have shown a mastery of the use of Flesh and Jade Shintai enough to be able to detach their heads and internal plumbing and let them fly through the air, and prove (through a secret and exacting vetting process) that they aren't akuma. They are known for their bombastic and flamboyant fashion sense, a right which was earned upon gaining the title.
In the New World of DarknessEdit
Penanggalans show up in the NWod 1e sourcebook "Night Horrors: The Wicked Dead" for Vampire: The Requiem.
Penanggalans are variants of vampire featured in "Rascals, Varmints & Critters 2", with the handwave that they're showing up in the Weird West because of Kang, the Chinese pirate king and warlock who is such a big-shot in the Great Maze.
AFMBE features Penanggalans as part of the many, many exotic undead from around the world in its "Atlas of the Walking Dead" splatbook.
Penanggalans have actually been a part of D&D for quite a long time; they first showed up officially in the Fiend Folio for AD&D 1e, which means they were originally part of the Fiend Factory in White Dwarf. They were updated to 2e in the Monstrous Compendium Fiend Folio Appendix, and got a "Necrology of the Penanggalan" in Dragon Magazine #222. They naturally made it into 3rd edition in the Oriental Adventures splatbook, and even made it into 4th edition in "Monster Vault: Threats to the Nentir Vale".
Whilst they haven't shown up officially in 5e yet, the fanmade "Monsters of the Orient" book on DM's Guild naturally features them, admittedly spelling their name as "Pennaggolan".
Being the most recognized Oriental Adventures type game on the market, Penanggalans are naturally a monster here.