Eta Carinae (aka η Car) is a binary star including
a luminous blue variable (LBV).
Its current apparent magnitude varies around 4, but an episode in
1843 increased it to -1 (the Great Eruption, which was basically
a supernova impostor) which resulted in a later surrounding nebula
(the Homunculus Nebula).
It is a candidate for a future supernova.
The other (known) star of the system is an O-type star.
Characteristics: