SurnameDB – The Internet Surname Database

Underlined words are explained in our glossary.

The surname Dempsey is generally accepted as being of Irish origins and therefore correctly O'Dempsey. There can be little doubt that most do derive originally from this source. However the name has also been long recorded in England, and there is a suggestion by eminent researchers that some of the English name holders may derive from some lost village called 'Dempsey or Demsey', however this is not proven. The Irish , was once one of the most powerful in Ireland, possessing great estates in the area known as 'Clanmalier', now the modern counties of Leix and Offally. James 1st of England and V1 of Scotland granted Terence O'Dempsey the title of Viscount Clanmalier, for the support of the clan during the many rebellions of the 16th and 17th century. The name is an spelling of the O'Diaomasach, which translates as 'The descendant of the proud one'. Curiously in 1170 the of the Dempsey's opposed the landings of , Earl of Pembroke, and, it is said, was the only Irish commander to be successful in such engagements.

List Ancestral records for:- O'Dempsey

At sometime in the following centuries the clan became loyal to the English crown, a loyalty that ultimately lost them all their lands when they supported the catholic James 11 at the battle of the Boyne. Here he was defeated by William of Orange. Early recordings of the surname include Lewis O'Dempsey in 1652 in Ireland, and Thomas Dempsey, married at St Anne's church, Westminster, in 1692. The the is that of a , a lion between two swords conjoined, hilts down. The first recorded spelling of the family name is shown to be that of Dermot O'Dempsey, which was dated 1193, founder of Abbey, during the reign of King Richard 1st of England, known as '', 1189 - 1199. Surnames became necessary when governments introduced personal taxation. In England this was known as . Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing of the original spelling.
Your A4 printed scroll

Surname scroll

O'Dempsey Surname Scroll

Printed A4 parchment scroll · 8.3 × 11.7 in

Enjoy this name printed onto our colourful scroll, printed in Olde English script. An ideal gift.

Buy 2 or more scrollsGet free shipping
  • Printed and dispatched within 5 working days
  • Royal Mail delivery to almost anywhere in the world
  • Research exclusive to The Internet Surname Database
See all photos and details →
The MyHeritage DNA testing kit

Partner offer

O'Dempsey is one branch. Find the rest in your DNA.

MyHeritage DNA shows your origins across 2,114 regions and finds relatives through shared DNA.

Explore MyHeritage DNA (opens MyHeritage in a new tab)

SurnameDB is a MyHeritage partner and may earn a commission.

Historical records

Records about the O'Dempsey family

SurnameDB is a MyHeritage partner and may earn a commission.