A Satarran, as he originally appeared to the crew of the Enterprise-D
The deception is revealed by a phaser blast
Commander Keiran MacDuff was an alias assumed by a Satarran who posed as the executive officer on board the USS Enterprise-D.
After altering the memories of the Enterprise crew and changing the computer records in 2368, MacDuff convinced the crew that they were at war with the Lysians, and urged the destruction of their mission objective, the Lysian Central Command. The Satarrans were at war with the Lysians for decades but could not destroy the facility because their weaponry was similar to the Lysians and Central Command was heavily guarded (by their standards).
MacDuff's personal mission failed when Captain Picard refused to fire on the, by Federation standards, defenseless Lysian space station. His suspicions were raised when the Lysian destroyer and Lysian sentry pods they encountered were no match for the Enterprise and questioned if they were really at war with them; after all, why would a species centuries behind them in weaponry be a serious threat? When MacDuff tried to overrule Picard's orders, he was hit by a phaser discharge by Commander Riker, revealing his true identity. Together, Riker and Worf were able to incapacitate MacDuff and prevent him from destroying the station.
MacDuff's faked identity states that he was born on September 27th, 2334, as son of Joseph and Les MacDuff on Gamma Canaris N. He entered Starfleet Academy in 2352 and graduated in 2356. (TNG: "Conundrum")
- Keiran MacDuff was played by Erich Anderson.