Tim Davie is set to step down as director-general of the BBC, he has announced.
His decision follows recent concerns over the corporation's impartiality, specifically regarding the editing of a speech by US President Donald Trump in a Panorama episode, raised this week.
Mr Davie confirmed his departure would not be immediate, stating he is "working through" timings to ensure an "orderly transition" over the coming months.
The BBC said Davie sent a statement to staff which said: “I wanted to let you know that I have decided to leave the BBC after 20 years.
“This is entirely my decision, and I remain very thankful to the chair and board for their unswerving and unanimous support throughout my entire tenure, including during recent days.
“I am working through exact timings with the board to allow for an orderly transition to a successor over the coming months.
“I have been reflecting on the very intense personal and professional demands of managing this role over many years in these febrile times, combined with the fact that I want to give a successor time to help shape the charter plans they will be delivering.
“In these increasingly polarised times, the BBC is of unique value and speaks to the very best of us.
“It helps make the UK a special place; overwhelmingly kind, tolerant and curious.
“Like all public organisations, the BBC is not perfect, and we must always be open, transparent and accountable.
“While not being the only reason, the current debate around BBC News has understandably contributed to my decision.
“Overall the BBC is delivering well, but there have been some mistakes made and as director-general I have to take ultimate responsibility.”
BBC chairman Samir Shah said: “This is a sad day for the BBC.
“Tim has been an outstanding director-general for the last five years.
“He has propelled the BBC forward with determination, single-mindedness and foresight.
“He has had the full support of me and the Board throughout. However, I understand the continued pressure on him, personally and professionally, which has led him to take this decision today. The whole Board respects the decision and the reasons for it.
“Tim has given 20 years of his life to the BBC.
“He is a devoted and inspirational leader and an absolute believer in the BBC and public service broadcasting.
“He has achieved a great deal.
“Foremost, under his tenure, the transformation of the BBC to meet the challenges in a world of unprecedented change and competition is well under way.”
