Romulan

The Romulans (Rihan: Rihannsu, "the Declared"; singular "Rihanha") were a humanoid species from the planet Romulus. They were an off-shoot of the Vulcans, their ancestors having left after rejecting the teachings of Surak. The Romulan state for most of their history was known as the Romulan Star Empire, a major power in their region of the galaxy. (Star Trek)

History
The Romulan species was devastated in 2387 by the Hobus supernova, which destroyed many of their planets, including their adopted homeworld Romulus, and killed billions of people. 

Star Trek: Freedom
In the mid to late 25th century, the Romulan Star Empire and the Federation was at the height of one of their tensest time periods. Captain Courtney Covaks defied orders and crossed the Romulan Neutral Zone into Romulan territory, making it to Romulus where she made the plea before the Romulan Senate and the Praetor to call for peace between the Federation and Romulan Star Empire. Much to the surprise of the Federation council, the Romulans agreed to open talks, resulting in a lasting peace between the two organizations, and the eventual entry of the Romulans into the Federation.

Romulans

 * List of known Romulans

Romulanos