蓝超巨星（BSGs）是恒星的恒星光谱分类中的第1级，光谱型为O或B型，属于超巨星的其中一种，是宇宙中温度及亮度最高的恒星。它们的温度与亮度皆非常高，表面温度为10,000－55,000°K，质量约太阳的10－150倍。O型早期的蓝超巨星是宇宙中最亮最重的恒星。蓝超巨星的半径通常在太阳的15-50倍之间，O型超巨星的半径通常不会大于太阳的30倍，只有少部分特超巨星会超过这个数据。B型蓝超巨星则更大一些，但一般也不会超过太阳的60倍大。已知直径最大的B型星是手枪星，直径是太阳的306倍。最有名的蓝超巨星是猎户座的参宿七，SN 1987A也是一次蓝超巨星爆炸造成的结果，这也是天文学家首次观测到蓝超巨星爆炸。

Hertzsprung–Russell diagram

Spectral type

Brown dwarfs

White dwarfs

Red dwarfs

Subdwarfs

Main sequence
("dwarfs")

Subgiants

Giants

Bright giants

Supergiants

Hypergiants

absolute
magni-
tude
(M_V)

Blue supergiants (BSGs) are hot luminous stars, referred to scientifically as OB supergiants. They have luminosity class I and spectral class B9 or earlier.

They are found towards the top left of the Hertzsprung–Russell diagram to the right of the main sequence. They are larger than the Sun but smaller than a red supergiant, with surface temperatures of 10,000–50,000 K and luminosities from about 10,000 to a million times the Sun.