(Sun-aside) the brightest star in the entire sky (from our location) - though it is only 26 times as luminous as our Sun, it appears so bright on account of its being only 8.5 light-years distant.
This star sits at the base of the neck of Canis Major, the Big Dog, which is why it is often known as the Dog Star. Its brightness actually throws off the whole scale by which stars are measured, because it's got an official magnitude rating of negative 1.6!