Lol Lucifer kills Odin in Supernatural season 5. That was unrealistic. Lucifer is only an angel. Odin is a fucking NORSE GOD and would rip Satan's head off with his bear hands! That is the truth.
Now that you mention this, yes, Supernatural is pretty hilarious from that part. There the Christian God is basically the mightiest thing that ever exsisted and every other cultures god is some significantly inferior physically killable demi-god. I suppose its understandable, since the main plot does mainly circle around chrisian beliefs and myths. And you couldnt really do it, if you threated all the gods equally. Since only one could have created humanity.