A fixed star of the first magnitude in the constellation Boötes.

the 4th brightest star and the brightest star in the constellation Bootes; 36 light-years from Earth

Arcturus (α Boo / α Boötis / Alpha Boötis) is the brightest star in the constellation Boötes, and the third brightest star in the night sky, with a visual magnitude of −0.05, after Sirius and Canopus. Because Alpha Centauri consists of two bright stars which are closer together than the limit of resolution of the human eye, Alpha Centauri actually appears brighter than Arcturus to the naked eye. It is the second brightest star visible from northern latitudes and the brightest star in the northern celestial hemisphere.

Arcturus is an avant garde metal band formed in Norway in 1987 under the name Mortem. In 1990, the band changed their name to Arcturus (meaning Bear Guardian), likely after the Behenian fixed star Arcturus.

In Isaac Asimov's Foundation Series, Arcturus is one of the major planets. It was capital of the Sirius Sector in the Galactic Empire, and later of the Arcturus Sector. It was falsely believed by a number of late Imperial Archaeologists such as Lameth to be the planet of origin of the human species.