|Sources: World of Warcraft: Cataclysm|
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.
Shadow priests, known for utilizing the powers of the Old Gods and the Void, can temporarily summon a merciless one through the talent.
In the present, the merciless were first seen during , where they were recruiting/possessing gilgoblins for the assault on the Abyssal Maw. Following Neptulon's capture in , 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.
|Julak-Doom <The Eye of Zor>||Controlling a flesh giant in the Twilight Highlands||Killable||Twilight Highlands|
|Mindbender Ghur'sha||Controlling Erunak Stonespeaker in the Throne of the Tides||Killable||Abyssal Halls, Throne of the Tides|
- Amorphic Cognitor
- Deep Subjugator
- Infesting Mindeater
- Jiao Spawn
- Parasitic Mindstealer
- Merciless Aberration
- Merciless One
- Sunken Terror
As a companion pet
- Main article: Syd the Squid
- 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.
- 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).