The leader of Ceredigion council, Ellen ap Gwynn, is to step down at the local government elections in May.
The Plaid Cymru councillor has been leader of the local authority since 2012.
The party has elected Bryan Davies, who represents Llannarth, as her successor as its group leader.
Ms ap Gwynn said she was “extremely proud of the work we have achieved during challenging times”.
The councillor for Ceulanamaesmawr was the first woman and first Plaid Cymru member to become leader of the authority.
“My focus has always been on improving the lives of the residents of Ceredigion; to make sure families can access an excellent education for their children in good quality schools, to attract new jobs, to boost skills in young people and to continue with our programme of investment to strengthen our local economy,” she said.
In 2019 she warned that mid Wales would become little but a “playground” for tourists unless plans to boost its economy succeeded.
Three years earlier she apologised for losing her temper during a BBC interview.
Plaid Cymru will be defending its position as the largest group on the authority when voters go to the polls on 5 May.