S Doradus is the brightest star in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. A hypergiant, it is one of the most luminous stars known (sometimes more luminous than −10 absolute magnitude), but so far away that it is invisible to the naked eye.
Some have speculated that S Doradus may be a binary star. However, the data present has proved to be inconclusive.
This star belongs to its own eponymous S Doradus class of variable stars (these classes are usually named after their prototypes); also designated as the class luminous blue variable or LBV. S Doradus exhibits long, slow changes in brightness, punctuated by occasional outbursts.