Philosopher king
From Tardis Wiki, the free Doctor Who reference
The Sixth Doctor referred to himself as a "wandering philosopher king in exile", further emphasising traits of wisdom, kindness and humility. Jack countered that he'd seen no such humility in the Doctor. (AUDIO: Piece of Mind)
Behind the scenes
The philosopher king is Plato's idea of a perfect state ruler, described in his Republic. A philosopher king, above all, would be a lover of wisdom and knowledge.
