VV Cephei

VV Cephei is a eclipsing binary star in the Cepheus constellation. It is 5,000 light years from Earth. 
VV Cephei A is one of the largest known stars, being a red supergiant. Its diameter is around 779 times that of the Sun. It is orbited by VV Cephei B, a blue star with 1325 times the Solar radius. If VV Cephei A were placed in the center of our Solar System, its radius would reach past the orbit of Mars.