Captain MacMillan (nicknamed Mac, callsign Alpha Six then later Baseplate) is a character from Call of Duty: Modern Warfare.
He is voiced by Zach Hanks in Call of Duty 4: Modern Warfare and by Tony Curran in Call of Duty: Modern Warfare 3.
MacMillan is a British SAS officer and former commanding officer and mentor of Captain Price (who was rank Lieutenant at his time). By MW3, MacMillan had become the Director of the British Special Forces. He's popular amongst CoD fans for his dense Scottish accent and sharp wit.