A shapeshifter who served as the chief of security on the station.
Odo is the shape-shifting security chief of Deep Space Nine, an enigmatic being who does not know his origins. Dry, rigid and fiercely devoted to justice, he keeps order on the station and maintains an uneasy rivalry with Quark.
He eventually learns he is a Changeling, one of the Founders who rule the Dominion, and the discovery pulls him between his loyalty to his friends and to his people. He develops a deep bond with Kira and later enters a romantic relationship with her, and he also forms a close friendship with Lwaxana Troi. During the war he is infected with a disease and his choices shape the fate of the conflict. He ultimately leaves to rejoin the Great Link to cure his people.
Odo's search for identity and belonging gives him one of the show's most moving arcs.