The surname Pettypool arose from a single Medieval family living in Essex, England. The name appears to have 'daughtered out' in England by the early 17th century. Apparently, a single Pettypool male, William, was the last to receive the name, and he immigrated from the London area to Virginia, USA in the mid 1650's. His son, also William, fathered two documented sons and from them all the known Pettypools in the world today appear to have sprung. In America from the late 17th century through the late 18th century, most lines of the family continued to be known either by Pettypool or Pettipool (the most common variant). Sometimes in written documents from this era, deviant spellings of these two names appeared (e.g. Petteypool, Pettiepool, Petepoole, etc.), but I would call them deviants and not true variants as it is not clear that the families themselves would have recognized them as valid and they appear mostly as singular instances.

After the Revolutionary War and the opening of the American western and southern frontiers in the late 18th and early 19th centuries, many branches of the family, particularly those that left Virginia for points west and south, started to use or at least be identified by an abbreviated form of the name, i.e. P.Pool. One branch of the family adopted the form P'Pool. It is not clear how or why this change arose. Perhaps the widespread use of abbreviated forms by legal clerks was adopted by the families themselves. Finally, in the mid to latter part of the 19th century, many branches only inconsistently used the P.Pool and P'Pool forms and the name became assimilated in some branches to the more common surname, Pool or Poole.