A Starfleet security officer who secretly joined the Maquis.
Michael Eddington is a Starfleet security officer assigned to Deep Space Nine at the start of the third season, played by Kenneth Marshall. Posted to the station as Starfleet's security liaison, he works alongside a resentful Odo and at first seems a loyal, by-the-book officer.
In For the Cause he is exposed as a Maquis agent when he steals industrial replicators meant for Cardassia and flees to join the movement. Convinced that the Federation betrayed the colonists of the Demilitarized Zone, he becomes a Maquis leader. Sisko becomes fixated on catching him, and in For the Uniform he finally forces Eddington's surrender by turning Eddington's own tactics against a Maquis colony.
In Blaze of Glory, after the Dominion and Cardassians have all but destroyed the Maquis, Sisko takes Eddington from prison to stop a supposed Maquis missile strike. The threat turns out to be a ruse to rescue the last Maquis survivors, and Eddington dies holding off Jem'Hadar soldiers so they can escape.