Daniel O'Neill

• Dan O'Neill (Gaelic footballer), Irish Gaelic footballer
• Dan O'Neill, American cartoonist
• Dan O'Neill, founder of Mercy Corps
• Dan O'Neill (writer), Alaskan author and journalist
• Daniel O'Neill (painter), Irish Romantic painter
• Daniel O'Neill (Royalist), Irish army officer, politician and courtier
• Daniel O'Neill (editor), editor and owner of the Pittsburgh Dispatch newspaper
• Daniel O'Neill (Illinois politician), member of the Illinois House of Representatives