The cabby who becomes Narnia's first king is Frank. In The Magician's Nephew, London cab driver Frank is transported to the newly created Narnia and crowned by Aslan.
Frank arrives when Digory Kirke and Polly Plummer accidentally bring Uncle Andrew's magical trouble into the new world. Frank's horse, Strawberry, becomes the winged horse Fledge, while Frank himself demonstrates practical good sense and kindness. Aslan chooses him to rule because he is an ordinary, decent man rather than a power-hungry adventurer.
Frank's wife, Helen, is brought from England and becomes the first queen. Together they begin Narnia's human royal line. Frank is also important genealogically: later Narnian and Archenland rulers descend from him, linking the world of Narnia to an ordinary London family at the dawn of its history.
Readers sometimes confuse Frank with Caspian or Tirian, who are later Narnian kings, or with Lune, who rules Archenland. Frank is specifically the first king, crowned at Narnia's creation in the prequel.