Preacher Witting is the Gatekeeper of Columbia and the man responsible for Booker's transformation into Zachary Hale Comstock in BioShock Infinite. After the Battle of Wounded Knee Booker came across Witting, who offers to baptized all his sins away. In the one reality Booker refuses, later becoming Elizabeth's father, and in another he accepts the offer, becoming Comstock.
In the reality where Booker became Comstock, Witting took on the role of Gatekeeper to Columbia, baptizing all those who wish to enter.