Senator O'Neil
- Australian Senate
- Bill O'Neill (New Mexico politician)
- Charles O'Neill (Pennsylvania politician)
- Deborah O'Neill
- Edward J. O'Neill (Rhode Island politician)
- Edward O'Neill (Wisconsin politician)
- Héctor O'Neill
- Illinois Senate
- Isabelle Ahearn O'Neill
- James O'Neill (Washington politician)
- Jerry O'Neil (politician)
- John O'Neill (congressman)
- Lottie Holman O'Neill
- Montana Senate
- New Mexico Senate
- New York State Senate
- Ohio Senate
- Pennsylvania State Senate
- Rhode Island Senate
- Senate of Puerto Rico
- William O'Neil (Wisconsin politician)
- William T. O'Neil
- Wisconsin Senate