Meegan McDonnell was a holographic crew member aboard the Federation starship Galen during its assignment with Project Full Circle. She was created by Reginald Barclay and Lewis Zimmerman to be a companion for The Doctor. However, knowledge of her holographic nature was kept secret from all aboard except Barclay. McDonnell was also programmed to emit false biological readings when scanned, making her appear human.
Shortly after the fleet's arrival in the Delta Quadrant, McDonnell was taken over by an Indign personality, the remaining neural activity of a long-dead Neyser. Under control of the entity, she escaped the ship in a shuttlecraft. (VOY novel: Unworthy)