Proxima Centauri (Latin proximus, -a, -um: meaning 'next to' or 'nearest to') is a red dwarf star that is likely a part of the Alpha Centauri star system and is the nearest star to the Sun at a distance of 4.22 light years. As the name suggests, it is located in the constellation of Centaurus.

Proxima Centauri is categorized as a flare star, as it undergoes random increases in luminosity because of magnetic activity. It only has about an eighth of the Sun's mass, and consequently it has a very low luminosity. Because of its proximity, the size of this star can be measured directly, giving a diameter only one-seventh the size of the Sun.