Sirius, in the constellation Canis Major, is the brightest star in the night sky. This is not however due to it's size or true brightness (it's absolute magnitude) but the fact Sirius is only 8.7 light years from Earth which in astronomical terms is quite close.
Image: Sirius' poisition in Canis Major
Sirius is actually two stars, a binary system comprising of Sirius A (The Dog Star) a white main-sequence star and Sirius B (The Pup-Star), a white dwarf star.
In Britain, Sirius is best viewed in late winter and appears as a very bright blue-white star south-east of the constellation Orion and is one of three stars which form the asterism The Winter Triangle.
 Brilliant Starsby Patrick Moore - ISBN 0-304-34903-8