The Romulan High Council was a high ranking body within the Romulan Star Empire that consisted of Romulans of high-caste birth who served as an advisory body to the Praetor of the Romulan Star Empire.

Lord Kazanak's father served on the council. (TNG novel: The Romulan Prize)

The novel was written before the concept of the Imperial Romulan Senate was introduced and has been overwritten by canon. However, its entirely possible that the High Council did not serve the same role the Senate and may have served a separate role.