Kevin Cahill, chief executive of Comic Relief for the past 19 years, has announced he will stand down later this year.
Cahill, who joined Comic Relief as director of education and information in 1990 and rose to become chief executive in 1997, said he would leave the charity once his successor was in place.
In a statement, Comic Relief said Cahill had been responsible for the creation of Sport Relief in 2002 and helped to turn Red Nose Day into "the biggest event of its kind in the world".
Cahill, who was appointed CBE in 2007, has led the charity through times of both significant growth and increased scrutiny, as in 2013 when a BBC Panorama documentary uncovered evidence that the charity had been investing millions of pounds in companies incompatible with its mission, including alcohol, tobacco and arms companies.
Comic Relief, registered with the Charity Commission under its legal name Charity Projects, said after a review that it would no longer invest in such companies and would be more transparent about its investments.
In a statement today, Cahill said he was incredibly proud of Comic Relief’s work, which would not have been possible without the "enormous efforts of all the staff at Comic Relief and the passionate support of the wider Comic Relief family".
He said: "Sport Relief and Red Nose Day have become two of the most successful regular fundraising events in the world, helping Comic Relief to raise over a billion pounds to fight for a just world free from poverty as well as providing some of the most iconic moments in television history."
Sir Lenny Henry, co-founder of Comic Relief, said Cahill had been a "truly inspirational chief executive" and would be sadly missed by all who worked with him.
The charity had an income of £84.4m in the year to the end of July 2014, according to its latest accounts filed with the Charity Commission.