Bettatan'ru was the name of a demon lord present within Romulan beliefs.
Background
Statue representations of Bettatan'ru could be found within the Romulan Palace on Romulus where it appeared as a horned humanoid creature with cloven hooves and black fangs where red smoke emanated. It always possessed a smiling face that often portrayed it as gloating over those who approach it. Its arms were typically outstretched as if it were attempting to grab those that came before it.
- Due to the nature of the dialogue and the fact that statues of the Ancient Ones were present within the palace, Bettatan'ru may have been considered a member of the Ancient Ones. Also, considering it was described as a demonic creature there is a possibility that Bettatan'ru and the Ancient Ones were part of the Host, a collective of 666 races that makes up the civilisation known as the Furies.
History
In Second History, a young Thea prayed to Bettatn'ru for a suitable handsome warrior to be a mate that was worthy of her.
As an adult and facing the possibility of the death of everyone due to the tampering of the timeline, Thea stated that her 'childhood friend' had abandoned her and her people in order to retreat to its steamy heaven. She also challenged Bettatan'ru to strike her down for turning her back on it. The statue representation did not do anything. (TOS novel: Killing Time)
- Though the events happened in the alternate timeline of Second History, presumably Bettatan'ru exists within the mainstream timeline of First History.