Steve Brown has resigned as chief executive of the Rugby Football Union, after 14 months in the role.
Brown succeeded Ian Ritchie in September 2017, but has announced he will leave the role at the end of the year.
Director of professional rugby Nigel Melville will be interim CEO until a replacement is appointed.
"I'm sad to leave, but the union is in good shape, with an excellent leadership team in place," Brown said.
"This has been a very difficult decision for me to make, and I informed the board earlier this week that the time is right for me to step down and take some time out."
After joining the RFU in 2011, Brown was promoted to chief executive after working as chief financial officer and managing director of the World Cup in 2015.
One of his first big decisions was to hand a contract extension to England boss Eddie Jones, which coincided with the team's poor run of form, while the RFU's finances have come under heavy scrutiny, with more than 60 members of staff made redundant, and cuts at grassroots level.
Despite the difficulties, Brown has remained a popular figure, with senior RFU staff understood to be devastated by his departure.
RFU chairman Andy Cosslett said: "Steve's tireless work ethic and selfless attitude has won him the respect of all who know him and the game will be extremely sad to see him go.
"He is a good man and a good friend to many of us. He leaves with our very best wishes and our sincere thanks."
Analysis - Baron's attack was final straw
Senior RFU figures are understood to be devastated by the news of Brown's departure - and strongly reject suggestions he has been forced out because of the financial difficulties at the union.
The chief executive is believed to have become weary and disillusioned with the sniping from RFU grandees such as Francis Baron, whose latest attack in The Times this week is thought to have been the final straw.
Brown's departure has no impact on Eddie Jones' position as England head coach. He signed Jones to a contract extension until 2021 - depending on England's performance at next year's World Cup, with a semi-final finish believed to be the minimum requirement.
The hunt for Jones' successor is being led by Melville, not Brown.