Daniel O'Sullivan
Daniel, Danny or Dan O'Sullivan may refer to:
- Daniel O'Sullivan (musician), English musician
- Daniel O'Sullivan (priest), Irish priest and theologian
- Danny O'Sullivan (Australian rules footballer)
- Danny O'Sullivan (boxer), English boxer
- Dan O'Sullivan (basketball), American basketball player
- Dan O'Sullivan (Gaelic footballer), Irish Gaelic footballer
- Dan O'Sullivan (historian), British author of ''Wikipedia – A New Community of Practice?''