Riley Aldrin Shepard was a cadet at Starfleet Academy in the 2370s. He was a member of the elite Red Squad.
In 2372, he helped to disable the global power distribution center in Lisbon, allowing Admiral Leyton to launch a coup attempt. (DS9:"Paradise Lost")
In 2373, Red Squad were assigned to crew the USS Valiant, on a training mission to travel around the Federation. Following the outbreak of the Dominion War, the Valiant found itself trapped behind enemy lines. When the commanding officers were killed, Cadet Tim Watters assumed command, and kept the ship behind enemy lines.
Shepard was awarded a provisional rank of lieutenant by the overzealous Watters, who ordered the crew to continue missions in Dominion space. Shepard and most of Red Squad were killed when the Valiant engaged a powerful Jem'Hadar battleship prototype and was destroyed. (DS9:"Valiant")
- Cadet Shepard was played by David Drew Gallagher. His name is derived from spaceflight pioneers, astronauts Buzz Aldrin and Alan B. Shepard.