Alpha Centauri (The Curse of Peladon)

Alpha Centauri was the Alpha Centauran delegate to Peladon when it applied for membership in the Galactic Federation. (S)he aided the Doctor in defeating Hepesh and Arcturus. (DW: The Curse of Peladon)

Fifty years later, Alpha Centauri was the Federation Ambassador to Peladon. (DW: The Monster of Peladon)