The universe is filled with enormous planets that make the Earth seem like nothing more than a speck of sand on a mountain. We don't even need to leave our solar system in order to find the behemoths that put our planet to shame. Take Jupiter, for example. This gas giant has 63 moons, some of which are larger than the other planets in the solar system (like the moon Ganymede, which is larger than the planet Mercury). Similarly, the Great Red Spot (Jupiter's largest storm) could swallow Earth twice over, while over 1,300 Earths could easily fit inside the planet itself.
To put it mildly, Jupiter is truly enormous. But of course, Jupiter isn't the reigning king of the solar system. Obviously, that title goes to our star—you could fit 1.3 million Earths inside the Sun. That may sound impressive, but (unsurprisingly) there are many stars that dwarf our Sun. In fact, there are stars that dwarf nearly our entire solar system....like blue supergiants.
To begin with, the terms "hypergiant" and "supergiant" are both a bit general. For the most part, these terms are loosely used to refer to the largest and most luminous (brightest and thus most energetic) stars in the universe. The exact term that one should use depends on the specific star that one is discussing (its size and luminosity). There are yellow hypergiants, red supergiants, blue supergiants etc.). You don't need all the specifications about where all the cutoff points are. For now, it suffices to say that the coolest stars are red stars, the hottest stars are blue, "supers" are a tad more luminous than "hypers," and hyper stars are the largest (regardless, hypers and supers are both amazingly large).
This means that blue supergiants are altogether impressive. Though they are not the largest known stars, these are the brightest and most energetic. They can have luminosities anywhere from about 10,000 to a million times that of the Sun. There, surface temperatures fall somewhere between 10,000–50,000 K. For comparison, the surface of our own Sun is a mere 5,700 K, so if a blue supergiant replaced our Sun, all life would be scorched from the surface of the Earth.
And as the name indicates, these stars are huge...super huge. Rigel is probably the best known blue supergiant. It is located in the constellation Orion and has about 20 times the mass of the Sun. It puts out about 60,000 times as much energy, and is 60 times bigger than our star. And there are stars that are far more impressive. Blue supergiants can reach sizes 1,000 times larger than the Sun. This means that, if one were in the center of our solar system, it would almost be wide enough to span Jupiter's orbit (in essence, it would eat nearly our entire solar system).
If you think that these stars are impressive, then you will really be blown away by red hypergiants. These are the largest known stars. NML Cygni is one of the largest that we've discovered. It has a radius about 1,650 times that of the Sun. If it were placed at the center of our Solar System, its surface would extend beyond the orbit of Jupiter—filling over half of the gap that exists between Jupiter and Saturn's orbit. So say goodbye to Mercury, Venus, Earth, Mars, Jupiter, and all of their various moons. And this doesn't even take into account the amazing solar storms that would emanate from this beast. If we were to consider all the stellar activity, few things in our solar system would have a chance of survival.
In the end, there are a number of stars that are larger and brighter than our own middling Sun; however, I still think that our's is a tad more impressive.
So far, our star is the only star—and our planet the only planet—that we know of that have given rise to life. And I think that makes them rather awesome.