The feared intelligence service of the Romulan Star Empire, which watches foreign enemies and Romulan citizens alike.
The Tal Shiar is the Romulan intelligence agency, known for its secrecy, its sway over the military and its readiness to arrest and interrogate disloyal Romulans. In Face of the Enemy, Deanna Troi is forced to pose as a Tal Shiar officer to help Romulan defectors escape.
In Improbable Cause and The Die Is Cast, the Tal Shiar joins the Obsidian Order in a secret attack on the Founders' homeworld, and the combined fleet is destroyed in a Dominion ambush in 2371. Its chairman Koval is later seen during the Dominion War, and Picard reveals that the Zhat Vash operates within it.