See related questions
the biggest thing in the universe that isn’t A galaxy is a black hole
Universe: It contains everything.
the universe, which is everything we know of.
sun is the brightest star in the galaxy
The sun is moving at an amazing speed. It is the biggest brightest star in the galaxy.
The biggest mass in the universe is the supermassive black hole at the center of the galaxy M87, which is estimated to be about 6.5 billion times the mass of the sun.
No. It isn't the smallest one, either.
universe, molecular cloud, galaxy, star, planet, asteroid,atom
As the question specifies brightness, the brightest star in the Universe is our Sun - because it is the closest star to us. The most luminous star is another question: See related question.
Obviously, the Universe is the biggest of that lot. Next biggest is "galaxy", then solar system, then star, then moon. A comet is usually bigger than a meteorite, but not always.
Most of the times, the brightest part of the galaxy is at the ceentre due the higher density of stars .Also if the galaxy is a spiral then the brightest part of the galaxy are the spiral arms because they are the star formation areas in the galaxy
A quasar will have the brightest galactic centre.