Belak
The Belak was a Romulan  warbird that was in service with the Tal Shiar in the late 24th century. The Belaks cloaking device was modified to prevent detection by Dominion sensors at speeds under warp 6. 

It was part of the joint Tal Shiar/Obsidian Order fleet that attacked the first  in 2371 during the Battle of the Omarion Nebula. In the first strike, the Belak lost main power, and the ship was subsequently destroyed. ()

Later when Captain Benjamin Sisko noted to Federation President Jaresh-Inyo that the Bajoran wormhole was "opening and closing for no apparent reason", Odo continued that they "didn't detect any ships coming through at the time," however added, "but the Dominion might have been using some kind of cloaking technology." When Jaresh-Inyo pressed the matter, with regards to his belief that the Dominion did not possess cloaking technology, Odo responded with the theory that "the combined Cardassian and Romulan fleet that the Dominion destroyed in the Gamma Quadrant was equipped with cloaking devices. Who knows what my people might have taken from the wreckage?." ()

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Romulan starships