- OLochlainns Irish Families - home of the Irish Genealogical Foundation and Olochlainns Irish Family Journal, free listing and bulletin board online.
- O'Kelly - research your Irish roots and discover Irish genealogical links.
- Oster - also including: Galliano, Kennedy, and Hickman families.
- Oshel
- O'Dea - also spelled: O'Day, Dee, or Day, includes family history, current news, and genealogical queries.
- Offringa
- Overend
- Orth - family history of Johann Peter Orth, born 1818, in Furstengrund, Hessen, Germany, and died in 1893 in Wallace Township, Perth County, Ontario, Canada.
- Odom
- Ouimet - Internet home of Les Descendants de Jean Ouimet, Inc.
- O'Mahony - with membership and event information.
- O'Brien - formed to promote the interests of all O'Briens who are descended from their progenitor, Brian Boru.
- Ohmer - genealogical research of the surname.
- O'Keeffe - features a comprehensive family tree of Georgia O'Keeffe.
- Olive - genealogy, history, reunions, coat of arms.
- O'Connor - family research and genealogy links.
- O'Flaherty - for history, genealogical questions, and contacts with other familiy members.
- Oglesby - also Anderson, Barker, Carpenter, Crawford, Druehl, Ellis, Hite, Kinzel, Lawhon, Meriwether, Naumann/Norman, Thornton and Yundt.
- Ohnmacht - McKercher Families of northeast Pennsylvania and Upstate New York.
- Oravecz - dedicated to families with variants of this surname. Including Oravec, Oravetz and others.
- O'Hearn - dedicated to the exchange of genealogical information from people around the globe searching the surname O'Hearn.
- O'Roughan - O'Ruadhain, Roan, Roughan, Rowan, Ruane genealogy, family history, pedigree and surname history.
- Oldham (2)
- Olzheim - in Dutch.
- Ortenburger and Hackstock - family history in the USA, Germany, Silesia, and the Russian Empire.
- Olree - also including: Evans, Hijman, Hymen, McCoy, Parker, Kislowski, and Malasinski.
- Odden - gedcom files, pictures, and maps of family genealogy.
- Oliver - with family tree and some photos.
- Ogle / Tasker / Ridout / Tayman - also Tayloe and Carter. Traces the genealogy of these Maryland, Virginia, and Washington D.C. families.
- Owens - tracing the descendants of Nathaniel Owens and Rebecca Massey.
- O'Neal - other surnames include: Carden, Cockriel, Ensor, Foy, Goodling, Isbelle, Moore, Paysinger, and Wheeler.
- Openshaw (1)
- Oulton - also Dyke, Winnard, Sinclaire, Rigby, Raper, Crook, and Jolley.
- Olmütz
Surname Research
Surname Listings
- Surnames A (a)
- Surnames B (b)
- Surnames C (c)
- Surnames D (d)
- Surnames E (e)
- Surnames F (f)
- Surnames G (g)
Useful Resources
...Usefull Links