Lucius O'Brien
Lucius O'Brien may refer to:
- Lucius O'Brien (died 1717)
- Sir Lucius O'Brien, 3rd Baronet, Member of the Parliament of Ireland
- Lucius O'Brien, 13th Baron Inchiquin, Irish politician and nobleman
- Lucius O'Brien, 15th Baron Inchiquin
- Lucius Richard O'Brien, Canadian painter
- Lucius O'Brien (priest), Dean of Limerick in the Church of Ireland