Vega
Vega, also designated α Lyrae (Latinised to Alpha Lyrae, abbreviated Alpha Lyr or α Lyr), is the brightest star in the constellation of Lyra, the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus. It is relatively close at only 25 light-years from the Sun, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood.
Bayer designation
Although the brightest star in Draco is Eltanin (Gamma Draconis), Thuban was assigned "alpha" (α) by Bayer because, due to precession, Thuban was the north pole star 4,000 years ago. Sometimes there is no apparent order, as exemplified by the stars in Sagittarius, where Bayer's designations appear almost random to the modern eye. Alpha and Beta Sagittarii are perhaps the most anomalously designated stars in the sky. They are more than two magnitudes fainter than the brightest star (designated Epsilon), they lie several degrees south of the main pattern (the "teapot" asterism), they are more than 20 degrees off the ecliptic in a Zodiacal constellation, and they do not even rise from Bayer's native Germany (while Epsilon and several other brighter stars do). The order of the letters assigned in Sagittarius does correspond to the magnitudes as illustrated on Bayer's chart; but the latter do not agree with modern determinations of the magnitudes.