The Beta Quadrant is the common designation for one-quarter of the Milky Way Galaxy when viewed from a point of view perpendicular to the plane of the galaxy. It extended ninety degrees spinward of an imaginary line drawn from the center of the galaxy, the galactic core, passing at least near the Sol System.
The Carina Arm and Norma Arms of the galaxy are located in that quadrant, as is the star NGC 5139.
- The major portions of the Klingon Empire and the Romulan Star Empire are located in the Beta Quadrant.
In 2293, the starship USS Excelsior, commanded by Captain Hikaru Sulu, completed a three-year exploratory voyage in the Beta Quadrant which included cataloging gaseous anomalies.
Seventy years later, Captain Lisa Cusak and the crew of the USS Olympia began a seven-year exploration voyage in the Beta Quadrant. Following this mission, the Olympia crashed on a planet in the Rutharian sector en route back to Federation space. While escorting a convoy to the Vegan system in 2374, the crew of the USS Defiant made contact with Cusak in 2371 via a temporal anomaly.
- The Rutharian sector was three days' travel away from the Vegan system, suggesting that both of these areas are in or near the Beta Quadrant.
When members of the Hierarchy captured Captain Kathryn Janeway and forced the Doctor to obtain Voyager's warp core for them, he impersonated Janeway and told Commander Chakotay a cover story involving a fictitious R'Kaal Imperium which supposedly controlled "thousands of parsecs from here to the edge of the Beta Quadrant."