Octans is named after the octant invented by the Englishman John Hadley around 1730. So it has sometimes been known as Octans Hadleianus. The octant is a navigational instrument incorporating a telescope. It is the predecessor of the modern sextant. The octant has its name because the instrument spanned an angular range of 45°, that is, one eighth of a circle. The modern sextant spans the larger angular range of 60°, one sixth of a circle.

Octans is notable only for containing the South Celestial Pole. There is no bright star near the Pole, and no star in Octans at all brighter than fourth magnitude.