Well, if by large you mean its physical size, I think the honor of that title has to go to the bright star called Mu Cephi which is a bright, naked eye star. If you were to put this star where the Sun is, its outer edge would extend 11.8 times the distance from the Earth to the Sun and reach the orbit of Saturn! Astronomers call this star, and a handful of similar stars 'hypergiants'. They are probably very old stars, 10 - 20 times the mass of our Sun, which in the future will become supernovae.