The largest known nebula is NGC 604 at 600-1220 light-years.
yes some of the largest nebulae in the milky way galaxy are the horsehead nebula and the eagle nebula.
A nebula galaxy does not exist.
Trifid is a nebula, not a star. For a the largest star, see related question.
Alpha Orionis in the Orion Nebula. Starother
A nebula is an interstellar cloud of dust, hydrogen and helium gas and plasma. A Nebula can be over 2.5 million light years across. The largest star is a mere 1.7 billion miles in diameter
The Crab Nebula is a nebula.
Flame Nebula Orion Nebula Eagle Nebula Omega Nebula Horsehead Nebula Eskimo Nebula Hourglass Nebula Pelican Nebula Helix Nebula (Eye of God) The list goes on. If you want to learn more I suggest checking out the NASA website or even looking up "nebula" on wikipedia where the have a list of the more notable nebula's.
The Crab Nebula is a supernova remnant and pulsar wind nebula.
Triffid Nebula, Eagle Nebula, Cat's Eye nebula