BBC Wales director Menna Richards will leave early next year after more than 10 years as its head, it has been announced.
BBC director general Mark Thompson said she combined "strong creative leadership with an excellence in management".
BBC Wales is home to some of the BBC's greatest programme successes recently, such as Doctor Who and Tribe, he added.
Ms Richards oversees all BBC Wales' services on radio, TV and online.
Welsh Secretary Cheryl Gillan paid tribute and said: "During a decade leading BBC Cymru Wales, Menna has been at the forefront of Welsh broadcasting and has made a major contribution to the thriving creative industries that are important to the economy of Wales.
"Under Menna's strong leadership, Wales has become a major creative centre for the BBC.
"The fantastic successes of networked programmes such as Gavin and Stacey, Dr Who, Torchwood and Coalhouse has given BBC Cymru Wales a reputation for excellence and placed it in prime position to reap benefits from the transfer of more drama and factual programme production out of London.
"The new BBC drama village, which begins production in Cardiff Bay next summer, will be a lasting legacy to Menna's vision and leadership of BBC Cymru Wales. I thank her for her huge contribution to broadcasting in Wales and wish her well for the future."
Writing to staff, Mr Thompson said: "Menna has been an outstanding director of BBC Wales, who has combined strong creative leadership with an excellence in management.
"I'd like to thank Menna personally for her superb professionalism, dedication and loyalty over the past decade."
Mr Thompson said she had led a "creative transformation at BBC Wales".
A new drama production centre is due to open in Cardiff Bay next summer, which will also be home to drama series Casualty.
Mr Thompson also pointed to the success of several high-profile programmes, and said Ms Richards had "strengthened journalism in both English and Welsh".
Russell T Davies, who oversaw the revival of Doctor Who for BBC Wales in 2005, said she had left her mark on Welsh culture.
"When I came back home, to work in Wales, it was amazing to meet Menna and to find a creative leader who was truly fearless. And great fun too," he said.
"But she's a crusader for talent, and has opened up opportunities for so many people, in so many ways, leaving Welsh culture immeasurably better and richer and bolder."
Ms Richards told BBC Wales staff she would be "very sad to leave this brilliant organisation".
"We have achieved so much together and I will forever count myself truly privileged to have worked alongside so many talented and committed people," she wrote.
"I never had any doubt that Wales had the talent to make a real difference both here in Wales and on the UK stage, and it's your passion and determination that has taken us on this extraordinary journey together.
"I'm absolutely certain that that same passion and determination will continue to drive BBC Wales forward."
Ms Richards had been managing director of HTV Wales before leaving for BBC Wales as controller in 2000.
Her achievements at BBC Wales included the opening of a new home for the BBC National Orchestra of Wales - BBC Hoddinott Hall - at the Wales Millennium Centre in Cardiff Bay.
BBC Wales has also broadcast several landmark series that explored Welsh life and history, including Coal House and, most recently, Snowdonia 1890.
"Serving the nation has always been at the heart of BBC Wales' vision," said Ms Richards.
"We make a huge contribution to the life of Wales in all its aspects: social, cultural and political.
"As the national broadcaster, our role in helping define a nation has never been so important or so precious."
Earlier this autumn, Ms Richards, originally from Maesteg, was appointed to the board of Welsh National Opera.
She was awarded an OBE for services to broadcasting in the 2010 New Year Honours.