Koval

Koval was a Romulan male and the Chairman of the Tal Shiar. He was also the top-ranking Federation operative in the Romulan Star Empire.

The Tal Shiar
Koval had become an operative of the Tal Shiar by the 2340s. In 2346, he discovered that in an interrogation conducted by Corbin Entek in which the Klingon Dirak revealed that the House of Kultan was developing biogenic weapons on Khitomer. Koval later arranged for an meeting with Jekri Kaleh, the head of the Tal Shiar, in Tal Shiar Headquarters. 

In 2360, Koval held the rank of Colonel in the Tal Shiar. In that year, he had Crofter Thamnos and his family develop a new strain of the Gnawing as well as a cure for it. 

Koval had risen to Chairman of the Tal Shiar by 2373. 

In 2374, Koval was in the Hall of State during a session of the Romulan Senate when a Senator insinuated that Neral was working for the Federation. (SS TOS (Blood Sacrifice))

In 2375, Koval worked with Luther Sloan and Section 31 to stop his formed lover Kimara Cretak, who the Federation considered dangerous, from ascending to the Continuing Committee, as well as elevating Koval to a much higher position. Sloan had convinced Julian Bashir that 31 was attempting to assassinate Koval and make him confide to Senator Cretak. Cretak was arrested and imprisoned for treason by Praetor Neral and the Committee. 

By 2377, Koval's Tuvan Syndrome had progressed to the point that he was seriously ill. 

Personal life
Using the money and authority from his early role in the Tal Shiar, Koval had built a home at the summit of Kor Thorn on Romulus. Only his aide Timol and Jekri Kaleh knew of the existance of the house. 

Tuvan Syndrome ran in Koval's family. 

Koval was in a romantic relationship with Kimara Cretak in 2360. They were of the same caste.