Daniel O'Brien

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

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