Alastair Lethbridge-Stewart

A parallel Earth's version of the Brigadier, Brigade Leader Lethbridge-Stewart was the head of the Republican Security Forces, and in turn was in charge of security at the Eastchester Scientific Labour Camp.

Biography
Unlike his counterpart, the Brigade Leader had a missing or damaged left eye, covered by an eyepatch. Section Leader Elizabeth Shaw acted under him. He captured and interrogated the Third Doctor, who had just arrived from his own universe. At first he had trouble believing the Doctor's story of having come from another universe.

With most of the base now covered in lava and his Earth itself threatened, he attempted to force the Doctor to rescue himself, Section Leader Shaw and Petra Williams, but Shaw shot him. (DW: Inferno)

He is mentioned in the episode The Wedding of River Song. While on the TARDIS, the Doctor calls the hospice where Brigadier Lethbridge-Stewart spent his last years. Unfortunately, he had passed away a few months before the time when the Doctor called. He reportedly died peacefully, spoke frequently about the Doctor, and always had his nurses pour him an extra glass of brandy in case the Doctor came by.

Behind the scenes

 * Nicholas Courtney, of course, played the part without the Brigadier's trademark (false) moustache.
 * Dialogue in Inferno only refers to the Brigade Leader by his title and last name, but not by his first name. Presumably, he had the same first and middle names as his counterpart, but this remains unclear.