The legendary Dragon
Like the Namekian Dragon Porunga, Earths Dragon Shenron can be summoned by gathering all seven of the Dragon Balls. Shenron can bestow any wish as long as it does not exceed the power of its creator and as long as the creator still lives. In Shenrons case, the creator is Kami. Of course, Kami was fused with Picollo while fighting the droids. Unlike Porunga, however, Shenron can only grant one wish per summoning. The new guardian, Dende, created his own Dragonballs.
The Namekian Dragon Porunga can be summoned after gathering all seven of the Namekian Dragon Balls. He is more brutal looking than the Earth Dragon, Shenron. Also, he has the power to grant three wishes instead of one, as long as the wishes do not exceed the power of the one who created the Dragon Balls, and as long as his creator lives.