Dame Esther Rantzen is stepping down as president of Childline due to ill-health, 37 years after she founded the charity.
She announced her departure from the charity after her lung cancer progressed to stage four.
The journalist and TV presenter served as a trustee for the charity until 2018, when she was appointed president.
Rantzen’s daughter Rebecca Wilcox, a journalist and BBC presenter, will take up the role temporarily.
Childline became a part of the NSPCC in 2006 and expanded to an online service in 2009.
It has 12 counselling centres around the UK that support the welfare of children and young people up to the age of 19.
The charity’s helpline aims to provide a safe, confidential place of help for children with no one else to turn to.
Peter Wanless, chief executive of the NSPCC, said: “Everyone at Childline and the wider NSPCC family sends Esther our very best wishes.
“For more than 35 years Dame Esther Rantzen has been the face and the heart of Childline, working tirelessly to set up, build and promote the service as a place where children and young people across the UK can go for free and confidential help and support.”
Wanless said the organisation would ensure that Rantzen was kept up to date “on all the great things that Childline continues to deliver”.
He said: “It is impossible to put into words the gratitude we feel for everything she does.”
Rantzen also founded The Silver Line in 2012, a helpline charity that offers information and advice to the elderly, which entered into collaboration with Age UK in 2019.
A spokesperson for Childline said Wilcox “feels deeply honoured to take on this role, she has grown up with Childline and enormously values the many achievements of the service, the dedicated staff and volunteers, all working to protect and support millions of children who have nowhere else to turn”.