How big can the stars in the universe be?

Stars in the universe are very different in size. While dwarf stars are only about as big as a planet, other supergiant stars may be 1,400 times larger than the Sun. For example, super-giant Vy Canis Majoris has a diameter of up to 2 billion km.

1. The brightest man-made star in the night is about to enter the universe in July
2. Which star lives the longest, brightest, biggest, . in the universe?