The name MacAlister means "son of Alister." Alister being
the gaelic equivalent of the more widely known name of "Alexandar", thanks
largely to "Alexandar the great" probably. There are a variety of spelling divergences
each of which is as correct as the next.
My branch of the family has spelled the name as McAllister for at least two hundred years.
One might logically ask, "why the divergence in spellings?" It's an interesting question.
It is likely that the name diverged as MacAlisters moved into populations in which the languages were as heavily written as they were spoken.
The gaelic language which the early MacAlisters spoke is primarily a spoken language (or so I am told) and as such it may very well have been likely
that MacAlisters seldom if ever saw their family name in written form as we have come to find common in many of our modern cultures.
In the case of my family, my guess is that based on the circumstances of their arriving in the New World
they would have had to either satisfy emmigrationary practices of colonial America or would have been recorded
in an effort to provide documentary evidence of their servitude obligation in payment for the Atlantic crossing
which various authors state was so common that "nine out of ten Scots, and Scotch Irish came to these shores in that manner."
(special thanks to John Yetter McCollister, click here to read his correspondance..)