The Algolians were a humanoid species native to the Alpha or Beta Quadrant. By the 24th century, their homeworld was a member of the United Federation of Planets.
In 2366, they attended the Trade Agreements Conference on Betazed. (TNG: "Ménage à Troi")
In 2367, an Algolian had a seat on the Federation Archaeology Council and attended the symposium on the USS Enterprise-D. (TNG: "Qpid")
The Algolians' appearance is similar to the Promellians, Yint's species and Pardshay's species
StarTrek.com suggests that Algolians originated from a planet orbiting Algol (Beta Persei), a Class B star. [1]; [2]
According to the Star Trek: Star Charts ("United Federation of Planets III") and the Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), there was a star system named Algol (Beta Persei), which might be the home system of this species, in the Alpha Quadrant.