Zek was the Grand Nagus of the Ferengi of the mirror universe when he journeyed to this universe.
In 2375, Zek and Maihar'du, Zek's Hupyrian personal assistant, crossed over to this universe hoping to make some profit exploring new business opportunities. However, they were captured by the Alliance. Quark's and Rom's counterparts rescued the pair, by bringing Regent Worf a cloaking device. (DS9: "The Emperor's New Cloak")