Odo , played by René Auberjonois, is a fictional character in the science fiction television series Star Trek: Deep Space Nine. He is a member of a shape-shifting species called Changelings and serves as the head of security for the space station Deep Space Nine on which the show is set. Intelligent, observant, and taciturn, Odo uses his unique abilities throughout the show to maintain security on the DS9 station and later aids the Bajoran people and the Federation throughout the Dominion War against his own people, the Founders. Source: Wikipedia (en)