Death Eye

Death Eyes were aberrations from the Underdark; little is known about them.

History
In the adventure hook The Incorruptible Light in the original Tal'Dorei Campaign Setting sourcebook, set in 812 PD, a group of drow refugees, after centuries of aberrant corruption in their own society, fled to the elf city of Lyrengorn with the hope that the skyswimmer's ceremony during the Moonweaver's Ribbons would cleanse them of their corruption and lingering madness. However, strange accidents worked to kill the skyswimmers and priestesses, and on the day of the winter solstice, two Death Eyes appeared from the Underdark with the intention of using the Moonweaver's Ribbons for their own nefarious ends.

Trivia
Beholders are aberrations known as "eye tyrants", and undead beholders are known as "death tyrants", but it is never explicitly stated whether the "aberrant Death Eyes" are related.