Star Trek: Discovery season 5 revealed more about the Breen than ever before, but two characters from Star Trek: Deep Space Nine already knew what the Breen looked like 800 years before L’ak (Elias Toufexis) removed his helmet. The Breen were first spoken of in Star Trek: The Next Generation, but it was Star Trek: Deep Space Nine that formally introduced the Breen as fearsome aliens wearing helmets and refrigeration suits. The Breen soon allied with the Dominion and became an existential threat to the United Federation of Planets.
