The largest known star is VY Canis Majoris [See Link] which has a diameter about 2,100 times larger than that of our Sun; this means about 9,300,000,000 Suns would fit inside (gaseous bodies like stars do not really have a definite 'surface'). See link for pictorial representation against our own Sun.
VY Canis Majoris can be found in the constellation Canis Major and is approximately 4,900 light years away.
See related link for a cool video showing how BIG VY Canis Majoris is!
In other galaxies there are probably larger stars.
You should clarify what you mean with "big" - biggest mass, or biggest diameter. In diameter, there are stars that have over a thousand times the diameter of our Sun. In mass, there are stars that have several tens of times the mass of our Sun.
There's a lot of uncertainty in measuring these things, since they're mostly too far away for us to see them as more than points of light.
However, currently VY Canis Majoris is probably the top contender. If it, rather than the Sun, were at the center of the solar system, Jupiter and all the planets closer to the Sun would actually be inside it... there's enough uncertainty in the measurement that it's possible that Saturn might be as well.
First you must define "biggest". Are you referring to the star's diameter? To its volume? (Larger diameter means larger volume, though.) Or perhaps to its mass? On the Wikipedia you can find lists of the biggest (largest diameter) as well as the most massive stars:
http://en.wikipedia.org/wiki/Most_massive_stars
http://en.wikipedia.org/wiki/Largest_stars
"Largest" here is used in the sense of "largest in diameter".
You can be quite sure that the largest star in the Universe is not known, and that the sizes of the known stars are not known exactly. You can find a list of largest known stars in the Wikipedia article "List of largest known stars" - together with a disclaimer (stating, for example, that the sizes of many of those stars are not known exactly). It is estimated that the largest star is about 1500 times the diameter of the Sun. Oh, and also be sure to distinguish between the star with the largest diameter, and the star with the largest mass.
"Antares" is probably the largest star visible with the naked eye.
However, the largest star may be "VY Canis Majoris" which is about twice as big as Antares, but is not visible with the naked eye. Estimating the radius of a star is not easy and there are a few other possible answers as to what the biggest star actually is.
See related questions.
We're not sure what the "oldest" constellations are. Most of the early constellations were named by the ancient Greeks, and it's possible that these names came from earlier Egyptian, Sumerian or Babylonian writings.
There are a few constellations that obviously "look like" the things they're supposed to represent. For example, the constellation Scorpio is very reminiscent of a scorpion, if you've ever seen a scorpion; the Egyptians were very familiar with scorpions. It requires very little imagination to see the constellation Orion as a human figure with a raised club.
That depends on how you define "object." There are supermassive black holes at the center of many (perhaps most, perhaps all) galaxies, and those would be likely candidates if you insist on it being a single discrete object. Even more massive, though it may not be a single "thing", is the Great Attractor, a something-or-other in approximately the direction of the constellation Norma that is massive enough to affect galaxies over a region hundreds of millions of light-years across.
We won't know that until we've observed all the stars in the universe and measured
the size of each one. Since there are an estimated 200 to 400 billion stars in our
Milky Way Galaxy alone, and several billion other galaxies outside of ours, that's
going to be a while, so we'll have to get back to you on it.
See related question for the largest star known.
Universe -> galaxy -> star -> planet
Universe: It contains everything.
Universe, galaxy,nebula,solar system, star, planet
Universe, Cluster, Galaxy, Star, Planet NB: Some stars are smaller than planets.
Twin dwarfs referred as 2M0939 is the dimmest star known
VY Canis Majoris is the name of the largest star that we know of in our universe.
Universe -> galaxy -> star -> planet
The largest known stars are the red supergiants or hypergiants. One example, the largest known star, is VY Canis Majoris.
We can only see stars that are relatively near-by. It would be more appropriate to ask about the largest known star. Stars are known that have about 2000 times the Sun's diameter, but it isn't known for sure which of them is the largest, since there is some uncertainty in the diameters of some far-away stars.
Universe: It contains everything.
None. There is no known center to the universe.
When the second largest known star, in the universe, goes supernova, this will occur. (Estimates range from this happening in the year 2012, all the way to one million years from now.) The name of this giant star is Betelgeuse.
Universe, galaxy,nebula,solar system, star, planet
We will never know the largest star in the Universe. The biggest star in our Galaxy is VY Canis Majoris.
There is no stationary star anywhere in the universe.
Universe, Cluster, Galaxy, Star, Planet NB: Some stars are smaller than planets.
Twin dwarfs referred as 2M0939 is the dimmest star known