William Yates was a Starfleet Lieutenant in the 24th century. In 2370, he was aboard the Federation starship USS Equinox when it was transported to the Delta Quadrant by the Caretaker.
His name was read in memoriam when the Equinox was discovered by Voyager in 2374 -- he had perished during the smaller vessel's besieged journey through that area of space. (VOY: "Equinox")
- Yates was not seen, merely mentioned in the dialogue.