McMullin/McMullen are variations of the Scottish name McMillan,
which is an Anglicized version of the patronymic name Mac Maolain,
from the given name Maolan, from mao = bald, tonsured.
It generally described someone who wore a tonsure and in a transferred sense, to the devotee of a certain saint.
Variations are McMillen, McMullan, McMullen, McMullin, McMullon, McMowlane, McMoylan.
Submitted by: Heather Moser, nee Craik