Jeffrey David Sinclair was a human Starfleet officer in the 23rd century. He eventually became a Federation ambassador. Sinclair was born in Bradbury City, Mars on 3 May 2218. He attended Starfleet Academy from 2236 to 2240. In 2258, Sinclair commanded Deep Space Station B-5, in the Euphrates Sector. The following year, he married his long-time girlfriend, freighter captain Catherine Sakai. In November, their son David Sinclair was born. After a diplomatic assignment in 2281, Ambassador Sinclair disappeared near the galactic rim. (Star Trek: Pendragon)