The Federation's negotiator in the bidding for the Barzan wormhole, who is taken ill through Ferengi trickery and replaced by Riker in the episode The Price.
Seth Mendoza is an experienced Federation diplomat. He appears in the third-season episode The Price.
He is sent aboard the Enterprise to bid for rights to what Premier Bhavani of Barzan II believes is the first stable wormhole, competing with the Caldonians, the Chrysalians' agent Devinoni Ral and an uninvited Ferengi party. Mendoza is doing well, and knows Riker as a formidable poker player.
The Ferengi DaiMon Goss removes him by slipping him a substance that provokes a violent allergic reaction. Confined to sickbay, Mendoza recommends that Riker take his seat. Riker holds his own, but Ral wins the contract, only for the far end of the wormhole to prove unstable.