Dragonball Z - Piccole's Powers
In one of the DBZ sagas (i forget which one), Piccole gets turned to stone. He is frozen for some time before Gotenks and Trunks come along. The careless youngens knock the stone Piccole over and he shatters. When the stone curse is lifted Piccole comes back to life, explaining that he can regenerate himself as long as his head is not destroyed. In the Cell saga, some of the cells that have been used to create Cell have come from Piccole. During the battle between Cell and Goku, Goku destroys the upper half of Cell's body, from the waist up is gone. Somehow Cell is able to regenerate himself, and claims that this is due to Piccole's regeneration ability. However, Cell's head had been completely destroyed, and as we know this needs to be unharmed in order for the regeneration to work.