Why would they change a character's name for TV? Yes that's his name. Don't know why they changed it to being his brother though, or changed Panis to being a good guy. The Rahl family has been evil overlords of the Midlands for centuries.
They started out good, in fact Nathan Rahl (who lives in the palace with the sisters of the light but they didn't show him for some reason) was pretty much the last of the good ones and he's 400 years old ... but the spell on the Palace makes him look like a man in his 30's.
Oh, and he's the one who writes the prophecies, not the Creator, all Rahls have some power, Nathan's is prophecy.