The IRW Terix was a Romulan warbird commanded by Sirol that competed with the Enterprise-D in 2370 to find the lost USS Pegasus in the Devolin system.
The Terix appears in the Next Generation episode The Pegasus. Starfleet Intelligence learns that the Romulans have found debris from the USS Pegasus, lost twelve years earlier, and Admiral Pressman is sent aboard the Enterprise to recover it first. The two ships meet in the Devolin system, where Picard and Commander Sirol exchange polite untruths about their reasons for being there.
When the Enterprise enters a fissure in an asteroid to reach the wreck, the Terix seals the opening and Sirol offers to take the crew to Romulus as guests.
Picard instead uses the illegal phasing cloak from the Pegasus to fly out through the rock, then decloaks in front of the warbird and admits the treaty violation.