The Romulan High Council was a high ranking government body created in the earliest days of the Romulan civilization, part of their Councillory in which the thirty most senior and ten most junior senators from the Grand Council were represented. (TOS - Rihannsu novel: The Romulan Way)
By the era of the Romulan Star Empire, the body referred to as the High Council 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)