Former party leader Paddy Ashdown was a "towering figure" in politics, the Welsh Liberal Democrats have said.
It follows the death of Lord Ashdown, aged 77, on Saturday following a short illness.
The former MP for Yeovil was the longest serving UK leader of the Lib Dems in the party's history, serving as leader between 1988 and 1999.
The Welsh Lib Dem leader Jane Dodds said he was "a true friend of the Welsh Liberal Democrats".
"We all owe Paddy a debt of gratitude for his role in rebuilding our party and ensuring the flame of liberalism continues to shine brightly," she said.
"Paddy enriched the lives of all who knew him. He will be missed by us all. Our thoughts are with his family at this difficult time."
So very sad to learn of the passing of Paddy Ashdown. A Liberal to the core he lead with passion and energy at a critical time for the party. On a personal level he was incredibly supportive encouraging and kind. Condolences to Jane and the family.— Kirsty Williams (@Kirsty_Williams) December 22, 2018
The Lib-Dem assembly member for Brecon and Radnorshire, Kirsty Williams, also extended her sympathies to Lord Ashdown's family, describing him as "a Liberal to the core" who led with "passion and energy".
The former Welsh Lib Dem leader Lord Mike German said the death "leaves an immense hole in British politics".
"He was a friend, and author, and a political guide throughout my life," Lord German told BBC Wales on Sunday.
"He was my mate on the Backbench in the House of Lords. His huge energy and enthusiasm infected all who knew him."