Main Body:
British and Irish Ombudsman Association

Ombudsmen in the UK:
Estate Agents Ombudsman
Financial Ombudsman Service
Financial Services Ombudsman Scheme for the Isle of Man
Housing Association Ombudsman for Scotland
Independent Police Complaints Commission
Legal Services Ombudsman
Local Government Ombudsman (England)
Local Government Ombudsman (Wales)
Northern Ireland Ombudsman
Northern Ireland Police Ombudsman
Parliamentary Ombudsman
Prisons and Probation Ombudsman
Scottish Parliamentary Ombudsman
Scottish Public Services Ombudsman
Welsh Administration Ombudsman
Scottish Legal Services Ombudsman

Main Body:
British and Irish Ombudsman Association

Ombudsmen in Ireland:
Ombudsman Ireland
Ombudsman Ireland (Information Commissioner)

Complaint Handling Bodies in the UK and Ireland:
Adjudicator's Office
Advertising Standards Authority
Energywatch
Independent Case Examiner
Independent Complaints Reviewer
Institute of Chartered Accountants of Scotland
Law Society of Scotland
Lay Observer for Northern Ireland
Legal Compaints Service (E&W)
Ofcom (Broadcasting)
PhonePay Plus - premium rate phone numbers and texts (formerly ICSTIS)
Royal Institute of Chartered Surveyors
Solicitors Regulation Authority
States of Jersey Administrative Appeals System

European Ombudsmen:
European Ombudsman