Who is the druid who brews the magic potion in the Asterix books?

In the original French version he is called Panoramix, but in the English language translations he is known as Getafix.

Getafix, the venerable village druid. Gathers mistletoe and brews magic potions. His speciality is the potion which gives the drinker superhuman strength. But Getafix also has other tricks up his sleeve...