Wales' Children's Commissioner Peter Clarke has died of cancer aged 58.
Peter Clarke said children worried about bullying more than anything
Mr Clarke pioneered the role in the UK of a children's "champion" when he took up his post on 1 March, 2001.
First Minister Rhodri Morgan has hailed the former director of Childline Cymru's "commitment" and said he had "blazed a trail for others to follow".
One of Mr Clarke's first challenges was to hold the long-running Clywch inquiry into claims of sex abuse by a drama teacher who had committed suicide.
His decision showed that he was unafraid to use the legal powers his office gave him.
Mr Clarke's report described how John Owen serially sexually abused pupils over a period of two decades at the Welsh medium school Ysgol Gyfun Rhydfelen in Pontypridd.
The Clywch report demanded major changes in protection for school children.
Mr Clarke went on record to say he was "severely disappointed'' by ministers' progress on his recommendation for a national advocacy unit for children.
In 2002, he published a report looking at the way in which social services departments in Wales dealt with complaints, particularly from children in care.
Mr Clarke said listening to children was a "key element" of his job
He also highlighted the issues of child poverty in Wales and bullying, as well as voicing concerns on topics ranging from the smacking of children to the building of schools on landfill sites.
Similar children's' commissioner posts have since been created for England, Scotland and Northern Ireland.
In his final annual report, he acknowledged that ill health had frustrated many of his plans.
However as recently as last November he held a series of meetings with children in Wales asking them what issues they wanted him to focus on.
Mr Clarke, who was born in Llandudno and lived in Carmarthenshire, considered a "key element" of his job was to spend time listening to children and young people.
His post was created by the Welsh Assembly Government after a report by Sir Ronald Waterhouse in 2000 about the abuse of children over a period of 20 years at children's homes in north Wales.
He described his role as "literally representing that to the people who make decisions, the people in authority and the general public."
First Minister Rhodri Morgan said: "Peter was very much a pioneer.
"He always placed the highest importance on listening to the views of children and young people and making sure that their voices were heard, and responded to, particularly by government at all levels.
"He could sometimes be tough and demanding as a champion for children but that was his job.
"He always fulfilled his duties with passion, dedication and commitment. He blazed a trail for others to follow."
Mr Clarke started military training at Sandhurst before choosing a career in social work in London and Brighton, and also studying at Sussex university.
In 1985, he became a community care adviser for the charity Scope before moving back to Wales in 1991 to join the National Schizophrenia Fellowship.
He then spent more than five years as director at Childline Cymru.
He had also served on voluntary organisations, as well as the appeals committee of the BBC's Children In Need.
Mr Clarke is survived by his wife Jenny and their two sons.