Merciless ones are octopus-like cyclopean parasitic aberrations related to the Old Gods, primarily found alongside the naga forces in Vashj'ir. They are capable of attaching themselves to (and/or devouring) the heads of sapient beings in order to enslave them. They have beaks. Apparently they are also quite smelly.
Merciless ones were seen in the past during  Visions of the Past: The Slaughter of Biel'aran Ridge, fighting alongside Ozumat and N'Zoth's faceless ones against the kvaldir.
In the present, the merciless were first seen during  Those Aren't Masks, where they were recruiting/possessing gilgoblins for the assault on the Abyssal Maw. Following Neptulon's capture in  Defending the Rift, Erunak Stonespeaker was abducted by the naga and enslaved by the merciless one Mindbender Ghur'sha within the Throne of the Tides. In the Twilight Highlands, the giant merciless one Julak-Doom is controlling a flesh giant.
The naga use merciless ones to enslave vrykul at Azuregale Bay in Suramar on the Broken Isles.
Shadow priests, known for utilizing the powers of the Old Gods and the Void, can temporarily summon a merciless one through the [Mindbender] talent.
As a companion pet
- Main article: Syd the Squid
[Syd the Squid] has a chance to drop from [Greater Darkmoon Pet Supplies], although it's possible it's simply a squid that uses the merciless one model, rather than an actual merciless one.
- The Parasitoid Sha use the merciless one model and share the ability to attach themselves to their victims' heads, but are considered to be sha nonetheless.
- The merciless ones resemble unarmored Daleks from the popular British science fiction program Doctor Who.
- While the merciless ones have been referred to as "demon squids" and described as "demonic", there is no other evidence pointing to a connection to true demons, and it's most likely just intended as a simple descriptive term.
This article or section includes speculation, observations or opinions possibly supported by lore or by Blizzard officials. It should not be taken as representing official lore.
- The merciless ones may be related to the n'raqi or "faceless ones", another ancient aquatic species loyal to the Old Gods.
- Due to their physical similarities, they may also be related to the squid-like kraken. Ozumat, a kraken patriarch enslaved by the naga, attached himself to the head of Neptulon to enslave him, and is therefore thought to be an enormous merciless one. The spawn of the kraken Jiao are also merciless ones (besides using the same model, they share the merciless' telekinesis).