In Star Trek's "mirror universe", Rom (portrayed by Max Grodénchik) is a Ferengi member of the Terran Rebellion attempting to overthrow the Cardassian-Klingon Alliance. He is the younger brother of Quark, who was killed in the Deep Space Nine episode "Crossover". Appearing in the third season episode "Through The Looking Glass", Rom had tried to persuade his rebel comrades into launching an attack on Terok Nor. The other rebels believed his plan to be unsound and that he was motivated primarily out of vengeance for his brother.
As it turned out, Rom betrayed the rebellion by informing Intendant Kira Nerys about Benjamin Sisko's plan to rescue Jennifer Sisko. In return for the information, Kira had Rom killed and pinned to a wall with a blade.