Star Wars, in episode IV, the death star destroy a planet, what is the name of this planet???

The planet was Alderaan.

It was the planet Alderaan, Princess Leia Organa's homeworld by adoption. Her adopted father, Senator Bail Organa, was one of the first senators to work against the empire and was one of the three senators to sign the official Declaration of Rebellion. Bail Organa perished on Alderaan that day. One of the facts that made the destruction of Alderaan so heinous was that they were an extremely peaceful and sophisticated planet. Also an intresting fact, Alderaan was the origin of the nerf, a herbivore used extremely widely as food (species survived because of export off world). The nerf is also the origin of the comment in empire strikes back when leia called han a something, something, scruffy looking nerf herder which would be approximately equal to saying that you were a pig farmer in terms of cleanliness factor.

The planet was called Alderan

Alderaan...the planetLeia was raised on by Senator Organa and his wife after Luke's and her birth on Tatooine

Ceti Alpha V, the planet that Kahn was on.

Aldaron

Alderaan,Leia's homeworld

Alderan.

Everyboy loves that Alderaanian show.

As everyone before me has said it was alderaan