Star Trek: 10 Strangest Alien Species
5. Changelings
One of the most compelling characters on Deep Space Nine was Odo, the Security Chief of the station and a shapeshifter. In his natural state, Odo was a liquid but he could take any shape, including energy forms. But for years he thought he was the only member of his species until the wormhole opened. Then, he found his people.
In some ways, he wished he hadn't.
Changelings, as they're called in the Gamma Quadrant, turned out to be the Founders of the Dominion. The Vorta and the Jem'Hadar worshiped them as gods while the rest of the Gamma Quadrant feared them. Even worse, the Changelings were the engineers of the war against various species in the Alpha Quadrant that killed millions.
While the idea of shapeshifters in Star Trek is not unheard of, the level of control Changelings had over their molecular structures was surprising. What made them truly odd was their outlook on "solids" and their almost compulsive desire to take over the galaxy. While they lost the war, they probably still should not have been trusted.