The former Grand Nagus of the Ferengi Alliance was at least 100 years old, and had a mute Hupyrian servant, Maihar'du, constantly at his side. The epitome of all that his race holds dear, Zek was as rude, blunt, arrogant, presumptive and greedy as his own wiles and position will allow. Still, while revered for his business lobes, in his latter years Zek had scandalously come to depend for business advice on his new love, Quark and Rom's mother Ishka, and faced down a Ferengi Commerce Authority inquest in 2373 to keep his job.

Zek faked his death in 2369 and named Quark his successor in order to test the reaction of his son and heir apparent Krax -- as anticipated, a disappointment. As a workaholic, he had not had a vacation in 85 years in 2369.

Despite the usual friction in UFP-Ferengi relations, Zek played a major role in early contact with the Dominion through his trade contacts with the Dosi and the Karemma, long before the Federation had information; with that leverage he was not above asking for a favor in return, such as the release of his nephew Belongo by Starfleet authorities on Aldebaran III. Zek shared with Sisko and Dax the distinction of being one of the few non-Bajorans to experience an orb encounter, but the short-lived benevolence that resulted in 2371 was so threatening to the modern Ferengi way of life that Quark confronted the Prophets himself to have him restored.

Zek suffered from ongoing vascular damage to the mucous membranes caused by his own use of using Hupyrian beetle snuff.

In 2375, Zek decided to retire and spend his old age on Risa with Ishka, so he came to Deep Space 9 to name Rom as his successor.