Brigadier Alistair Gordon Lethbridge-Stewart was brought to us superbly by Nicholas Courtney. He is one of the founders of UNIT, and serves as commander of the British contingent. He was at first, reluctant to accept the continuing aid of the Doctor, but over time, the Brigadier became one of the Doctor's greatest friends and his principal ally in defending the Earth. The Brigadier first appeared in 1968 opposite the Second Doctor and his final appearance was alongside the 7th Doctor in 1989.  He did reappear in the Sarah Jane Adventures.  he was an amazing character and always brilliantly played.