(coexisting on another dimensional plane)
Rom was a Ferengi mercenary in the mirror universe. He fought in the Terran Resistance Forces during the Terran Rebellion against the Klingon-Cardassian Alliance, seeking revenge against the Alliance for the death of his elder brother, Quark. Compared to his primary universe counterpart, Rom was much more aggressive and devious.
As part of a plan to get Benjamin Sisko aboard Terok Nor, Rom pretended to defect to the Alliance and revealed that Sisko, who had been believed dead, was planning to come to the station. The Alliance, using Rom's information, managed to capture Sisko and "Smiley" O'Brien, and bring them to the station, which was exactly what the rebels wanted. Rom was to pilot their escape ship once Sisko and Smiley had rescued Jennifer Sisko from the Alliance.
Unfortunately, Elim Garak was suspicious of Rom and ordered him tortured into revealing the true plan. Rom was then executed, and his body was left impaled upon an airlock door as a warning. (DS9: "Through the Looking Glass")
Upon visiting the mirror universe in 2375, the Rom of the primary universe expressed sadness at the death of his counterpart. He told his brother Quark that he would have liked to have met himself. (DS9: "The Emperor's New Cloak")