A member of the team that built the Enterprise-D at Utopia Planitia, who murdered two colleagues and killed himself in the nacelle, leaving an empathic imprint that claims another life in 2370.
Walter Pierce appears in the seventh-season episode Eye of the Beholder. During the ship's construction he found that Marla Finn, the woman he loved, was involved with another man, William Hodges. He killed them both and then threw himself into the plasma stream, which destroyed the evidence. The deaths were never explained.
Pierce had a Betazoid grandmother, and the violence of the moment left a telepathic trace in the nacelle. Eight years later it drives Lieutenant Kwan to suicide and draws Deanna Troi into a long hallucination.
In that vision Pierce is alive and serving in engineering, and Troi relives his jealousy with Worf in the place of the unfaithful lover. He was played by Mark Rolston.