Beta Thoridar was a location in Klingon space, in the Beta Quadrant.
In 2256, its location was labeled on the star chart "Alpha/Beta Quadrant Overview" in the ready room aboard the USS Discovery. This star was located within the territory of the Klingon Empire. (DIS: "Magic to Make the Sanest Man Go Mad", "The War Without, The War Within")
A year later, its location was labeled on the star chart showing the trajectory of Lieutenant Spock's shuttle. (DIS: "An Obol for Charon")
In late 2367, at the start of the Klingon Civil War, the House of Duras gathered a large fleet near this location while preparing to launch an offensive against Gowron's forces. (TNG: "Redemption")