It's tough to definitively say which nebula is the most famous, as fame can be subjective and dependent on factors like cultural influence and scientific significance. However, some strong contenders for the title of "most famous nebula" include:

* The Orion Nebula (M42): This bright and colorful nebula is visible to the naked eye in the constellation Orion. It's one of the most studied and photographed nebulae due to its proximity and active star formation.

* The Crab Nebula (M1): This supernova remnant is famous for being the first astronomical object identified with a historical supernova event, observed by Chinese astronomers in 1054 AD.

* The Eagle Nebula (M16): This nebula is home to the iconic "Pillars of Creation," a striking image captured by the Hubble Space Telescope that showcases the birth of new stars within its gas and dust clouds.

* The Trifid Nebula (M20): This nebula is notable for its tri-lobed structure, caused by a combination of gas, dust, and young, hot stars.

Ultimately, which nebula is considered the most famous might depend on personal preferences and areas of interest. But these four are definitely among the most recognized and widely discussed nebulae in astronomy and popular culture.