Meaning of Last Name

McAllister (disambiguation) McAllister is a surname from Scotland and northern Ireland which is the anglicized form of Gaelic Mac Alasdair or son of Alasdair. Alasdair is the Gaelic form of the first name Alexander. According to [ancestry.com], as of 1920, it is most prevalent in the northeastern, southern and western parts of the United States. In the United Kingdom, it is most prevalent in northern Scotland as of 1891.