Proconsul was the common title given to the official in the Romulan Senate directly below the Praetor.
Former Romulans to hold this position within the Romulan Star Empire during the latter half of the 24th century include Proconsuls Merrok, Neral and Hiren.
Claudius Marcus of the Roman Empire-like state on planet 892-IV also held the title proconsul, and had significant influence over his people. (TOS: "Bread and Circuses")
As with other governmental terms in the Romulan Empire, the title of Proconsul is derived from the Roman title of Proconsul. In Rome, a Proconsul was a former Consul who had been assigned a province or a high-profile military command (as Pompey requested after his consulship) as a reward for their service to the Roman state. The term was diminished but retained under the Roman Empire.