The Dullahan (デュラハン, Dyurahan) is a humanoid liminal race most commonly known for their removable head.
Famed as "Heralds of Death", it is a Dullahan's job to escort the souls of the dead from the mortal realm into the afterlife. However, it has yet to be publicly confirmed whether or not this is actually true or simple mythological theory.
Privately, both Lala and a Dullahan associated with The Eight Brothers have exhibited knowledge and supernatural abilities to interact with/ward off Death and travel through the realms of the afterlife.
- Dullahan are one of the more humanoid of liminal species, possessing the same basic anatomy as a human baring the removable skull. However, they possess some traits that give them an otherworldly appearance such as black sclera, pale hair, blue skin.
- How a dullahan's head receives proper blood flow despite being detachable is currently a medical enigma. According to one theory, there's an additional heart inside their head that pumps blood, similar to fleas. In addition, it is medically unknown how the body can act of its own accord (often with a completely different personality) when detached from the head.
- As their head attaches and detaches at the neck. The connection between their head and neck is fundamentally weak, as such, their heads are frequently at risk of falling off. However, when a Dullahan's head is removed, they can still feel what is happening to the body itself.
- Teleportation: Dullahan are able to switch between the worlds and appear wherever they want. However, this ability seems to be limited when the head is separated from the body.
- Soul Reaping: While there is no scientific evidence that Dullahan are a "Harbringer of Death", Dullahan can actually bring the souls of the deceased from the realm of mortals to the afterlife. For this purpose, they use their scythes to separate the connection between the Ghosts and the objects that they still anchor them with the world of the living. Because of this, many Ghosts fear them very much.
- If a Grim Reaper is hit by a scythe of a Dullahan, he fade away into smoke, although it is not known what will happen to the Reaper afterwards, or whether it may even be "killed" by this.
- One of The Eight Brothers is dating a Dullahan girl. She likes to watch the third episode of Puella Magi Madoka Magica, which is infamous for having a decapitation scene.
- Dullahans appear near the houses of people about to die and throw a basin of blood on them when they open the door. However, this is only mentioned in The Eight Brothers, so it is unknown whether this information is canon for the Dullahan in Monster Musume, as Lala never mentioned this detail.
- Dullahans (also called Gan Ceann) are taken from Irish mythology. They are a type of Unseelie Fae, which are mischievous or outright malevolent spirits. They carry their head under their arm which is said to grin constantly. They typically ride carriages which are decorated with funereal objects such as bone-crafted wheels and covered in dried human skin. They are said to appear to those about to die in which they will say the person's name, causing the victim to drop dead instantly. It is also impossible to run from a dullahan as all doors and locks will open for them, though even a single piece of gold is said to repel them.
- The concept of a female Dullahan like Lala is actually very unusual because in the most legends, Dullahan are male.
- As stated in the Dullahan profile from MonMusu Collection 11, despite their detachable head, Dullahan are not undead like Zombies, but rather living creatures. It is also stated that they are an extremely rare Liminal species and also one of the most mysterious.
- Although Dullahan are referred to as "Heralds of Death", the fact that Dullahan are living beings indicates that they can die themselves.