This topic might have a better name.
No idea about the first name, but DWMSE 14's notes on Tardisode 8 variously spells the surname McMillan and McMillen.
Talk about it here.
Tina MacMillin was the Comissioner of the Sanctuary Base 6 crew and the Galis Expedition. She sent Captain Walker and his crew to retrieve the energy source on Krop Tor to sustain "the Empire". (WC: Tardisode 8)