- Military, intelligence
- Dan "Sandow" O'Donovan (1890–1975), Irish Republican Army figure
- Donal II O'Donovan (died 1639), the O'Donovan of Clann Cathail, Lord of Clancahill
- Donal III O'Donovan (died 1660), Irish Confederate Wars
- Donal IV O'Donovan (died 1705), Williamite War in Ireland
- Jeremiah O'Donovan (died 1709), O'Donovan of Clanloughlin, Registrar for the Admiralty (Ireland) under James II
- Jeremiah O'Donovan Rossa (1831–1915), Fenian, Irish Republican Brotherhood figure
- Jerome X. O'Donovan (1944–2014), US Marine Corps captain, New York City councilman
- Morgan John Winthrop O'Donovan (1893–1969), O'Donovan of Clancahill
- Morgan William II O'Donovan (1861–1940), O'Donovan of Clancahill
- Richard II O'Donovan (died 1829), O'Donovan of Clancahill
- Seamus O'Donovan (1896–1979), Irish Republican Army figure
- Government
- Daniel O'Donovan (MP Doneraile), represented the Manor of Doneraile in James II's Patriot Parliament
- Denis O'Donovan (born 1955), Irish politician, former Cathaoirleach of Seanad Éireann
- James O'Donovan, forensic scientist to the Garda Technical Bureau of the Garda Síochána
- John James O'Donovan, better known as Seán O'Donovan, (1893–1975), Irish Fianna Fáil politician and Veterinarian
- Patrick O'Donovan, (1977), Irish Fine Gael politician
- Reubin Askew (Reubin O'Donovan Askew) (1928–2014), American politician
- Timothy O'Donovan (1881–1951), Irish politician, Cathaoirleach of Seanad Éireann
- William O'Donovan (1886–1955), British Conservative Party politician
- Business & Finance
- Val O'Donovan (1936–2005), Cork-born Canadian electrical engineer, businessman, co-founder of COM DEV and Chancellor of the University of Waterloo
- Religion
- Academia
- Sport
- Ambrose O'Donovan, (1962), former Gaelic footballer
- Conor O'Donovan, (1962), former Irish hurler
- Darragh O'Donovan, (1995), Irish hurler
- Domhnall O'Donovan, (1988), Irish hurler
- Fachtna O'Donovan, (1921–1995) Irish Gaelic footballer
- Gary O'Donovan (1992), Irish rower
- John Francis O’Donovan, (1918–1999) Irish chess master
- Niall O'Donovan, Irish rugby union coach
- Ollie O'Donovan (b. 1966), Irish rallycross driver
- Paul O'Donovan, (1994), Irish rower
- Roy O'Donovan, (1985), Irish professional footballer
- Entertainment
- Aoife O'Donovan, (1982), Irish-American singer and songwriter.
- Frank O'Donovan, (1900–1974), Irish actor, singer and songwriter
- Maeve O'Donovan (b. 1990), singer-songwriter from Limerick, Ireland
- Máirín O'Donovan, (1936), Irish actress, singer, and dancer
- Noel O'Donovan, (1949–2019), Irish actor
- Ross O'Donovan (born 1987), animator and co-host of YouTube webseries, Steam Train
- Fictional
- Other
- Barra Ó Donnabháin (1941–2003), Irish language columnist, The Irish Echo
- Brian O'Donovan, (1980), Irish journalist
- Daniel O'Donovan of Mahoonagh and Feenagh, was the hereditary chief of the remnants of the Ui- Donnabhain of the Uí Fidgenti,
- Edwin O'Donovan (1914–2000), American art director
- Fred O'Donovan (theatre producer) (1930–2010), Irish theatre producer and businessman
- Fred O'Donovan (actor) (1884–1952), Irish actor, film maker and theatre manager
- Gerard O'Donovan, (1958), Irish author
- Gerald O'Donovan (1871–1972), writer
- Ímar Ua Donnubáin, or Ivor O'Donovan, a legendary and celebrated petty king, navigator, trader, and reputed necromancer of 13th century Ireland
- Mary Jane O'Donovan Rossa, (1845–1916), Irish poet and political activist
- Michael Francis O'Donovan (1903–1966), Irish author Frank O'Connor
- William Rudolf O'Donovan (1844–1920), American sculptor