| A fifteenth-century entrepreneur : Germyn Lynch, fl.1441-1483 | O'Neill, Timothy, 1947- | Article in Book | | 1988 |
| A note on the Tullamore town improvements, 1860 | O'Neill, Timothy P. | Article in Journal | | 2006 |
| Aghaboe, c.600-1800 A.D. | O'Neill, Timothy, 1947- | Article in Journal | | 2004 |
| An eviction in Kinnitty: Republican social agitation and the new Fianna Fáil government, 1932-1933 | O'Neill, Timothy | Article in Journal | | 2014 |
| Book-making in early Christian Ireland | O'Neill, Timothy, 1947- | Article in Journal | | 1989 |
| Cholera in Offaly in the 1830s | O'Neill, Timothy P. | Article in Journal | | 2003 |
| Clare and Irish poverty, 1815-51 | O'Neill, Timothy P. | Article in Journal | | 1974 |
| Columba the scribe | O'Neill, Timothy, 1947- | Article in Book | | 1997 |
| Columcille: a royal and holy bookman of the sixth century | O'Neill, Timothy, 1947- | Monograph or Collective Volume | The Wild Apple Press | 2010 |
| Doing local history | O'Neill, Timothy P. | Article in Journal | | 2001 |
| Edmund MacRichard Butler: books and warfare in fifteenth-century Ireland | O'Neill, Timothy, 1947- | Monograph or Collective Volume | The Wild Apple Press | 2012 |
| Edmund MacRichard Butler: books and warfare in fifteenth-century Ireland | O'Neill, Timothy, 1947- | Article in Journal | | 2015 |
| Famine evictions | O'Neill, Timothy P. | Article in Book | | 2000 |
| Fever and public health in pre-Famine Ireland | O'Neill, Timothy P. | Article in Journal | | 1973 |
| Fish, historians and the law: the Foyle Fishery case | O'Neill, Timothy P. | Article in Journal | | 2009 |
| From fax to vellum : producing manuscript books in the 21st century | O'Neill, Timothy, 1947- | Article in Book | | 2012 |
| Gigginstown and crown lands in Westmeath in the early 1800s | O'Neill, Timothy P. | Article in Book | Geography Publications | 2022 |
| Handing away the trump card? Peadar O'Donnell, Fianna Fáil, and the non-payment of Land Annuities campaign, 1926-32 | O'Neill, Timothy M. | Article in Journal | | 2008 |
| Initial wanderings: continuity and development of the smaller initials in Irish manuscripts, c.500–c.1500 | O'Neill, Timothy | Article in Book | | 2017 |
| Irish trade in the later middle ages: a survey | O'Neill, Timothy, 1947- | Thesis | | 1979 |
| Life and tradition in rural Ireland | O'Neill, Timothy P. | Monograph or Collective Volume | Dent | 1977 |
| Merchants and mariners in medieval Ireland | O'Neill, Timothy, 1947- | Monograph or Collective Volume | Irish Academic Press | 1987 |
| Minor famines and relief in County Galway 1815-1925 | O'Neill, Timothy P. | Article in Book | | 1996 |
| Navan and the cholera epidemic of 1832 | O'Neill, Timothy P. | Article in Journal | | 2020 |
| Navan: the Earl of Essex, Baroness de Ros and the Crown lands of the early nineteenth century | O'Neill, Timothy P.
| Article in Journal | | 2022 |
| Offaly : history and society : interdisciplinary essays on the history of an Irish county | | Monograph or Collective Volume | Geography Publications | 1998 |
| Overseas trade | Childs, Wendy R.O'Neill, Timothy, 1947- | Article in Book | | 1987 |
| Piracy off the southern and western coasts of Ireland in the later middle ages | O'Neill, Timothy, 1947- | Article in Journal | | 1980 |
| Poverty in Ireland in the first half of the nineteenth century | O'Neill, Timothy P. | Thesis | | 1971 |
| Poverty in Ireland, 1815-45 | O'Neill, Timothy P. | Article in Journal | | 1973 |
| Psalms and psalm books | O'Neill, Timothy, 1947- | Article in Book | NA | 2013 |
| Quills, inks and vellums | O'Neill, Timothy, 1947- | Article in Book | | 2009 |
| Recently discovered fragments of an Irish double Gallicanum-Hebraicum psalter, probably ninth century | O'Neill, Timothy, 1947- ; McNamara, Martin | Article in Journal | | 2023 |
| Reframing the republic : republican socio-economic thought and the road to Fianna Fáil, 1923-26 | O'Neill, Timothy M. | Article in Book | | 2015 |
| St Gallen scripts | O'Neill, Timothy, 1947- | Article in Book | NA | 2025 |
| The Castle of Offerlane, Castletown, Co. Laois | O'Neill, Timothy | Article in Journal | | 2022 |
| The Catholic church and relief of the poor, 1815-45 | O'Neill, Timothy P. | Article in Journal | | 1973 |
| The charities and famine in mid-nineteenth-century Ireland | O'Neill, Timothy P. | Article in Book | NA | 1999 |
| The famine in Offaly | O'Neill, Timothy P. | Article in Book | | 1998 |
| The Irish art of calligraphy : a step-by-step guide | O'Neill, Timothy, 1947- | Monograph or Collective Volume | Royal Irish Academy | 2024 |
| The Irish famine of 1822 | O'Neill, Timothy P. | Thesis | | 1965 |
| The Irish hand : scribes and their manuscripts from the earliest times | O'Neill, Timothy, 1947- | Monograph or Collective Volume | Cork University Press | 2014 |
| The Irish hand : scribes and their manuscripts from the earliest times to the seventeenth century with an exemplar of Irish scripts | O'Neill, Timothy, 1947- | Monograph or Collective Volume | Dolmen Press | 1984 |
| The lithographic manuscript facsimiles of the Royal Irish Academy | O'Neill, Timothy, 1947- | Article in Book | NA | 2018 |
| The Ó Longáins : last of the hereditary scribes of Ireland | O'Neill, Timothy, 1947- | Monograph or Collective Volume | Wild Apple Press | 2013 |
| The pen and the sword in ancient Ireland | O'Neill, Timothy, 1947- | Article in Journal | | 1999 |
| The persistence of famine in Ireland | O'Neill, Timothy P. | Article in Book | | 1995 |
| The Rices of Mountrice : solicitors' records of an epigonal family | O'Neill, Timothy P. | Article in Journal | | 1996 |
| The Roscrea missal : the writing of a manuscript book | O'Neill, Timothy, 1947- | Article in Journal | | 1983 |
| Tools and things machinery on Irish farms 1700-1981 | O'Neill, Timothy P. | Article in Book | | 1982 |
| Trade and shipping in the Irish sea in the later Middle Ages | O'Neill, Timothy, 1947- | Article in Book | | 1989 |