Centaurus is the name of a constellation. (Often, the name Centauri is used, too). It is the home of our closest neighbor: Alpha Centauri is the nearest star system, and therefore is often referred to as Alpha Proxima. It is only 4.5 light years away, and actually consists of three stars: Alpha Centauri A, B and C.
A and B are a close binary system, and are gravitationally bound to C. (So A/B are a distant binary with C).
At this moment, Alpha Centauri C is the Sun's nearest neighbor, which is why it is often called Proxima Centauri (See Proxima Centauri).
Alpha Centauri A is the brightest of the three. It is also known as Rigil Centauri or as Toliman.
Several planets circle A/B, and three of them are inhabited. One of them is a desert planet, and there has been some speculation that this might be the 'real' Serpo. It is unclear whether C has planets, but at least one contactee claims having met extraterrestrial visitors from a planet in orbit around C. (See Proxima Centauri).
At least three species are known in the Alpha Centauri system:
One source mentions a total of 19 different races in the system, including a reptilian race.
There also are rumors that an operational star gate connection to Alpha Centauri exists.
The name Centauri is Latin, yet refers to creatures in the ancient Greek mythology that were half horse, half human. (See: centaur)