A •
Aisling Clíodhnadh O'Sullivan (born 1984), Irish comedian, actress, and screenwriter •
Andy O'Sullivan (Irish republican), Irish republican hunger striker
C •
Camille O'Sullivan (born 1975), Irish singer •
Cormac O'Sullivan, fictional character •
Cornelius O'Sullivan (1841–1907), Irish brewer's chemist
D •
Daniel O'Sullivan (disambiguation), several people •
David O'Sullivan (disambiguation), several people •
Denis O'Sullivan (golfer) (born 1948), Irish golfer •
Denis J. O'Sullivan (1918–1987), Irish Fine Gael TD from Cork •
Denise O'Sullivan (born 1994), Irish footballer •
Derry O'Sullivan (1944–2025), Irish-language poet •
Diarmuid O'Sullivan (born 1978), Irish sportsman •
Donal O'Sullivan (disambiguation), several people •
Donal Cam O'Sullivan Beare (1561–1613), Irish chieftain •
Donie O'Sullivan (journalist) (born 1991)
E •
Eddie O'Sullivan (born 1958), Irish rugby union coach and footballer •
Edward William O'Sullivan (1846–1910), Australian journalist and politician •
Eoghan Rua Ó Súilleabháin (Owen Roe O'Sullivan, 1748–1782), Irish Gaelic poet •
Eugene D. O'Sullivan (1883–1968), American Democratic Party politician from Nebraska
G •
Gearóid O'Sullivan (1891–1948), Irish teacher, Irish Republican Army officer, barrister and Sinn Féin and Fine Gael politician •
Gerald Robert O'Sullivan VC (1888–1915), Irish soldier in the British Army, recipient of the Victoria Cross •
Gerry O'Sullivan (1936–1994), Irish Labour Party TD •
Gilbert O'Sullivan (born 1946), Irish-born, UK-based singer-songwriter, who had several hits in the 1970s •
Gillian O'Sullivan (born 1976), Irish race walker •
Grace O'Sullivan (born 1962), Irish environmentalist and politician •
Graham O'Sullivan, Kerry Gaelic footballer
H •
Harry Sullivan (baseball) (1888–1919), Major League Baseball pitcher •
Harry Stack Sullivan, American psychologist and psychoanalyst
J •
J. T. O'Sullivan (born 1979), American professional football player •
Jacquie O'Sullivan (born 1960), British singer and songwriter •
Jan O'Sullivan (born 1950), Irish Labour Party politician, currently a Teachta Dála (TD) for Limerick East •
Jeremiah O'Sullivan (1842–1896), Irish-born American Roman Catholic bishop •
Jerry O'Sullivan (disambiguation), several people •
John O'Sullivan (disambiguation), several people •
Sir John O'Sullivan (c. 1700 – c. 1760), a professional soldier in the service of France, known for his involvement in the Jacobite rising of 1745.
K •
Kevin O'Sullivan (baseball) (born 1968), American college baseball coach
L •
Laura O'Sullivan (born 1991), Welsh footballer •
Louise O'Sullivan (born 1973), Irish telecommunications executive •
Lance O'Sullivan (born 1963), New Zealand jockey, retired
M •
Maggie O'Sullivan (born 1951), British poet, performer and visual artist •
Marcus O'Sullivan (born 1961), Irish coach and former middle-distance runner based in the United States •
Mary Blanche O'Sullivan (1860 – ?), American teacher, writer and editor •
Maureen O'Sullivan (1911–1998), Irish cinema actress •
Maurice O'Sullivan (disambiguation), several people •
Michael O'Sullivan (disambiguation), several people •
Michael J. Sullivan (born 1961), author •
Mícheál Ó Súilleabháin (1950–2018), Irish composer and musician •
Mickey O'Sullivan (1932–2012), American college baseball coach •
Muiris Ó Súilleabháin (1904–1950), Irish writer; author of autobiography
Fiche Blian ag Fás (Twenty Years A-Growing), a description of life on the Great Blasket Island.
N •
Nóirín O'Sullivan, first female Commissioner of the Garda Síochána
P •
Paddy O'Sullivan (1918–1994), female Special Operations Executive spy during World •
Pádraig O'Sullivan, Irish Fianna Fáil politician •
Pat O'Sullivan, American amateur golfer who won the 1951 Titleholders Championship •
Patrick O'Sullivan (born 1985), Canadian-born American professional ice hockey player •
Patrick O'Sullivan (disambiguation), several people •
Paul O'Sullivan Band (formed in 2014), Pop-Rock band where all four members are named Paul O'Sullivan. •
Peter O'Sullivan (disambiguation), several people
R •
Richard O'Sullivan (born 1944), English actor, notable for his sitcom roles in the 1970s and 1980s •
Ronnie O'Sullivan (born 1975), English professional snooker player
S •
Sean O'Sullivan (disambiguation), several people •
Seumas O'Sullivan (1879–1958), Irish poet and editor of
The Dublin Magazine •
Shawn O'Sullivan (born 1964), Canadian boxer •
Siobhan O'Sullivan (1974–2023), Australian political scientist and political theorist •
Sonia O'Sullivan (born 1969), Irish Olympic runner, Sophie's mother •
Sophie O'Sullivan (born 2001) Irish Australian runner, Sonia's daughter •
Stephanie O'Sullivan (born 1959), Principal Deputy Director of National Intelligence (USA)
T •
Terence Patrick O'Sullivan (1913–1970), English civil engineer •
Thomas C. O'Sullivan (c. 1858–1913), New York politician and judge •
Timothy O'Sullivan (Fianna Fáil politician) (1899–1969), Irish Fianna Fáil Party politician •
Timothy H. O'Sullivan (c. 1840–1882), American Civil War photographer •
Toddy O'Sullivan (1934–2021), Irish Labour Party politician •
Tyrone O'Sullivan (1945–2023), Socialist and Chairman of Goitre Tower Anthracite Ltd., the owners of Tower Colliery.
V •
Vince O'Sullivan (born 1957), American racewalker •
Vincent O'Sullivan (American writer) (1868–1940), Decadent American writer •
Vincent O'Sullivan (New Zealand writer) (1937–2024), New Zealand poet
W •
Wayne O'Sullivan (born 1974), Irish soccer player in Australia •
William S. O'Sullivan (1928–1971), Irish-American gangster == See also ==