The Kriosian system (also known as the Krios system) was an inhabited planetary system in the territory of the Klingon Empire, in the Beta Quadrant. The system contained the inhabited planet Krios Prime. This system was located on the border of Federation space in the region between sectors 21166 and 22079.

The USS Enterprise-D visited the system twice, in late 2367 and in 2368. (TNG: "The Mind's Eye", "The Perfect Mate")

According to the Star Trek Encyclopedia (4th ed., vol. 1, p. 445), the Kriosian system was a Klingon protectorate. It was the only Klingon protectorate bordering Federation space.
Krios, the primary of the Kriosian system, was located in the Beta Quadrant on a star chart seen in the Star Trek: Discovery episode "Magic to Make the Sanest Man Go Mad".
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