Alistair Gordon Lethbridge-Stewart, fully Brigadier Sir Alistair Gordon Lethbridge-Stewart, generally referred to simply as the Brigadier, is a fictional character in the British science fiction television series Doctor Who, created by writers Mervyn Haisman and Henry Lincoln and played by Nicholas Courtney. He is one of the founders of UNIT, an international organisation that defends Earth from alien threats, and serves as commander of the British contingent. Presented at first as reluctant to accept the continuing aid of the Doctor, over time the Brigadier became one of the Doctor's greatest friends and his principal ally in defending Earth.

Henry Soskin, better known as Henry Lincoln, was a British author, television presenter, scriptwriter, and actor. He co-wrote three Doctor Who multi-part serials in the 1960s, and — starting in the 1970s — inspired three Chronicle BBC Two documentaries on the alleged mysteries surrounding the French village of Rennes-le-Château — and, from the 1980s, co-authored and authored a series of books of which The Holy Blood and the Holy Grail was the most popular, becoming the inspiration for Dan Brown's 2003 best-selling novel, The Da Vinci Code. He was the last living person to have written for Doctor Who in the 1960s.