Tarquin Zian was a smuggler of the Twi'lek male variety, active during the era of the Galactic Empire. He operated the ship Red Fang as its sole crew member. Prefect Dengless Rinn of Kallistas reached out to Zian, seeking assistance in a planned overthrow of Governor Linrec. Zian acted as a go-between for Rinn and the Mantis Syndicate: he was to supply Rinn with armaments for the coup, in exchange for payment in the form of illicitly acquired Kallistan gems.
Zian was also responsible for the transport of bounty hunter Demos Traxen to Kallistas; Traxen's objective was to locate an Alliance operative on the planet. Zian opted for a route that minimized the risk of encountering Imperial forces, however, by the time Traxen arrived, the Rebel agent had already been apprehended. Later, Rinn issued a bounty for the pirate Jondrell Inx, hiring Traxen along with two other bounty hunters, Sirenas Firil and Chandrex Grenn, to fulfill it. Due to his lack of complete faith in the bounty hunters, Rinn specifically tasked Zian with monitoring their activities.