Leading politicians have paid tribute to former Plaid Cymru president Gwynfor Evans, who has died aged 92.
Current party president Dafydd Iwan said without him Wales "perhaps would not be counted as a nation at all".
Labour First Minister Rhodri Morgan described Plaid's first MP as "a good and gentlemanly figure".
Tory Nick Bourne called him one of the most significant Welsh figures of modern days, and Lib Dem Mike German said he dedicated his life to Plaid.
Mr Evans was Plaid president from 1945 to 1981, became the party's became Plaid's first MP and helped create the Welsh language channel S4C after threatening to starve himself to death.
Mr Iwan said: "The news has been met with great sadness by all in Plaid Cymru who have been motivated by Gwynfor over the years to work for Wales and to create a nation we can all be proud of.
"For Plaid Cymru members and supporters, young and old, Gwynfor Evans has been Plaid Cymru's spiritual leader and will continue to be so.
"It is impossible to underestimate Gwynfor's unique contribution to building Plaid Cymru into the party it is today."
Mr Iwan said Mr Evans single-handedly guided their party in the 1950s and '60s, and "without Gwynfor Evans at the helm Plaid Cymru may not have survived to see electoral success in later years.
Gwynfor Evans changed the political climate by becoming an MP
"His influence was felt beyond the confines of party politics. Wales would not be the nation it is today - perhaps would not be counted as a nation at all - if not for Gwynfor Evans."
"Gwynfor Evans has had a huge influence on my political beliefs. He was a national leader in every sense of the word.
"His wisdom and guidance will be sorely missed but his legacy will live forever. Our thoughts at this time are with his wife, Rhiannon, and all his family."
Mr Morgan said: "We attended the same college at Oxford and I can remember an interesting discussion regarding his family links with the Dan Evans family in Barry.
"Although his relationships with Labour MPs were not always positive, there is no gainsaying his massive contribution to Welsh public life, and particularly in raising the profile of Wales and Welsh issues throughout his long career in Welsh and British politics."
Welsh Secretary Peter Hain said: "Gwynfor Evans made a distinguished contribution to Welsh public life and will be remembered particularly for his advancement of the Welsh language."
'End of a chapter'
Assembly Presiding Officer Lord Elis Thomas, also a former Plaid president, said Mr Evans' major contribution was becoming an MP "as a sign of the times for my generation".
He said the Carmarthen by-election was the beginning of the making of Plaid and devolution. Lord Elis Thomas said he often disagreed with Mr Evans over such issues as the S4C hunger strike, but he was a determined man who stuck to a decision once he made it.
Mr Bourne said: "Wales has lost one of its most significant figures of modern times. Gwynfor Evans was a highly respected figure who made a major contribution to Welsh politics.
"His record on delivering Welsh language broadcasting for Wales is of particular importance."
Mr Evans took up writing after standing down as party president
Mr German said: "Gwynfor served his party well and was able to bring them into electoral success.
"He earned respect from across the political spectrum. His passing marks the end of a chapter in Welsh political history".
Ann Clwyd, Labour Cynon Valley MP since 1984, said: "He was a gentleman at all times, and I was very fond of him. Over the years he strived over his party and he was very brave.
"He enjoyed a long life and had a family whom he was very proud of. I'm glad that he enjoyed such a long life, but I feel deep sadness today".
Conservative Lord (Wyn) Roberts of Conwy said: "Through his threat to go on hunger strike, Gwynfor forced the government to make a U-turn and renew their promise (to create S4C). He was not willing for that promise to dissipate.
"What he did most certainly influenced the government's decisions in the end. His contribution was substantial."