Former Ombudsman Kevin Murphy has died at the age of 75 following an illness.
Mr Murphy was a former senior civil servant in the Department of Finance and the former Department of the Public Service, before he was appointed the country's second Ombudsman.
He was also appointed the first Information Commissioner, following the passing of the Freedom of Information Act.
Current Ombudsman Emily O'Reilly paid tribute to her predecessor.
In a statement, she said he was a great champion of people "ill-served by the country's public administration".
Ms O'Reilly added: ''Kevin exemplified everything that is good about the public servant and the public service. He did his work diligently, thoughtfully and modestly.
''The values that should be embedded in our public service were deeply embedded in him, and his legacy will be a renewed effort on the part of this office towards honouring those values and his memory through our own service to the public.''