John Walter Jones, the first chief executive of the Welsh Language Board and a former chair of S4C, has died aged 74.
He helped draft the Welsh Language Act in 1993, which enshrined the right to the language being treated equally alongside English in public life.
He went on to steer the language board from its inception until 2004.
In addition to his role at the S4C Authority, he was also a familiar voice on BBC Radio Cymru.
Born in the Moelfre area of Anglesey, he went to school in Bangor before studying economics at Cardiff University.
It was as a civil servant in the Welsh Office that he worked on the legislation that established the Welsh Language Board to promote Welsh and help enforce the new laws.
The board saw its responsibilities transferred to the Welsh Government after the Senedd was set up, and later those powers passed to the Welsh Language Commissioner.
Between 2014 and 2018, Mr Jones presented a lunchtime discussion programme on BBC Radio Cymru.
Tributes were paid to Mr Jones by the current chairman of the S4C television authority, Rhodri Williams.
Mr Williams was also chair of the Welsh Language board during Mr Jones' tenure as chief executive.
"John was passionate about Wales and the Welsh language, as passionate as any language campaigner.
"He was responsible for putting the Welsh Language Board on its feet and ensuring that it stood alongside other bodies dealing with public policy areas."