(1) Alistair MacLean, 1922-1987, thriller author and screenwriter, The Guns of Navarone.
(2) Alistair MacLean, 1885-1936, father of the preceding, author of Hebridean Altars: The Spirit of an Island Race.
Please do not combine or assign the books by the following authors with Alistair MacLean: John Denis, Simon Gandolfi, Alastair MacNeill, Hugh Miller, and Sam Llewellyn. All have written books based on movie outlines that were originally written by Alistair MacLean (1922-1987).
There is also an author called Mrs. Alistair MacLean whose possible relation to the first Alistair MacLean is uncertain. What is certain is that she was not Alistair MacLean himself, and should not be catalogued without the "Mrs."
According to http://military.wikia.com/wiki/Alistair_MacLean, The Snow on the Ben was not written by MacLean as Ian Stuart, but by another author by that name: There was confusion around MacLean's pseudonym "Ian Stuart". A thriller titled Snow on the Ben by "Ian Stuart" was published by Ward in 1961, the same year as The Dark Crusader, but this was actually by an English author – Ian Stuart (1927–1993), who also wrote as Malcolm Gray. MacLean used the pseudonym only once more (on The Satan Bug, 1962).