S4C's director of commissioning Rhian Gibson has resigned, the Welsh language channel has confirmed.
Ms Gibson joined S4C in 2006 and was responsible for commissioning programmes and series, such as dramas Teulu and Pen Talar.
She also commissioned Cyw, the pre-school children's series.
S4C chairman John Walter Jones said that he respected Ms Gibson's decision and thanked her for her service and contribution over the last four years.
In a statement, Ms Gibson said that S4C faced a new chapter and wished S4C and the production companies all the best for the future.
Her resignation is the latest development in a turbulent period for the channel, that is waiting to learn if it will face sever budget cuts during next week's Comprehensive Spending Review.
The channel's chief executive Iona Jones stepped down in controversial circumstances earlier this year.