Daniel or Dan O'Brien may refer to:
Politicians and nobles Daniel O'Brien, 1st Viscount Clare (1577–1663), MP for County Clare, younger son of Connor O'Brien, 3rd Earl of Thomond Daniel O'Brien, 3rd Viscount Clare (fl. 1670–1691), son of Connor O'Brien, 2nd Viscount Clare Daniel O'Brien, 4th Viscount Clare (died 1693), son of Daniel O'Brien, 3rd Viscount Clare Daniel O'Brien (Jacobite) (1683–1759), Irish Jacobite soldier and diplomat Daniel Pitt O'Brien (1900–1957), Secretary of State of West Virginia
Sportspeople Athletes Dan O'Brien (born 1966), American decathlete Dan O'Brien (footballer) (1884–1917), Australian rules football player Dan O'Brien (pitcher) (born 1954), American baseball player Dan O'Brien (soccer) (born 1986), American soccer player Danny O'Brien (gridiron football) (born 1990), American college football quarterback Coaches / executives Dan O'Brien (American football) (born 1963), American college football coach and administrator Dan O'Brien (baseball coach) (born 1971), American college baseball coach Dan O'Brien Sr. (1929–2017), American baseball executive, general manager of Rangers, Mariners, Angels Dan O'Brien (baseball executive) (born 1953 or 1954), American former baseball executive, general manager of Reds; son of Dan O'Brien Sr.
Writers / journalists Daniel O'Brien (comedian) (born 1986), American humorist, writer and comedian Dan O'Brien (author) (born 1947), American author and rancher Dan O'Brien (playwright) (born 1974), American playwright Dan O'Brien (sports journalist), American sports journalist, author and screenwriter Danny O'Brien (journalist) (born 1969), British technology journalist
See also Danny O'Brien (disambiguation) Danielle O'Brien (born 1990), Australian ice dancer