Gul Nador was a Cardassian gul, a starship commanding officer, in several of the parallel universes encountered by Lieutenant Worf in 2370.

In one of those realities, Nador's starship, a Galor-class vessel, had manipulated the Argus Array to spy on the Federation.

When in another reality the USS Enterprise-D investigated the failure of the Argus Array, Nador's ship approached the Enterprise and Nador contacted it. He uttered his concern, that Starfleet's flagship was so close to the Cardassian border and wanted an assurance that the Argus array was not used by the Federation to survey the Cardassians. (TNG: "Parallels")