Tom Nellis was a male Human Starfleet officer in the 23rd century. He served in the operations division aboard the Antares, under the command of Captain Ramart. Nellis was the ship's first officer and navigator.
In 2266, Nellis and Ramart beamed aboard the USS Enterprise with Ramart and their passenger, Charles Evans, recently of Thasus. During Charlie's stay on the Antares, Nellis enjoyed having him aboard, or so he claimed to James T. Kirk. In reality, Charlie was exerting his learned psychokinetic powers over Nellis and the rest of the Antares' crew, as he had during his stay there.