The First Great Cat, Ra.

The MAU AA is the Guardian of the legendary Tree of Life, a divine tree that keeps the universe in balance. Ra was the first MAU AA, or Great Cat. who guarded the Tree of Life in the beginning of time. Devouring it was Apep, the demon serpent's greatest desire.
In Ra's prime, he would take the form of the Great Cat and beheaded his older brother, Apep, who would take the form of the Great Serpent when he attempted to devour the tree and plunge the world into chaos.