Amanda Mealing is taking a break from Casualty after seven years playing Connie Beauchamp on the medical drama.
The actress joined the long-running BBC One series in 2014, moving from sister show Holby City, where she had played the same character for six years.
Future episodes will see Beauchamp embark on a career break and put her personal life ahead of work.
Recent months have seen her relationship with Jacob, played by Charles Venn, fall apart under the stress of her high-pressure job as clinical lead, while she tries to steer Holby City Emergency Department through the coronavirus pandemic.
Mealing said: “It has been the most remarkable privilege to play Connie for the last 18 years.
“When she first hit our screens there were few female leads that weren’t ‘the wife of…’, ‘the mistress of…’ or needed ‘rescuing’.
“Most important for me is knowing that Connie has inspired so many women and young girls to seek careers, seek independence and strive to be their best.”
Beauchamp has been a fixture of the Holby City and Casualty universe since 2004, when she debuted in the former series as a cardiothoracic consultant.
Over the years the character has risen through the ranks, become a fan favourite and appeared regularly across both series.
Mealing will appear on screen in Casualty until late March, show bosses said.
Deborah Sathe, senior head of content production for Holby City and Casualty, said: “We are going to miss Amanda playing chief of the ED Connie.
“Connie has led the ED, her team, and our Casualty audience through Covid.
“The quest to restore Casualty to our screens was not an easy one, and we owe a huge debt to Amanda and the whole team for delivering some of the most extraordinary episodes Casualty has ever broadcast.
“We look forward to welcoming Connie back on to our screens in due course.”
The medical drama returned last month with an episode that showed the hospital facing “extraordinary times” as coronavirus reached its emergency department.
The BBC initially suspended production in March 2020, along with EastEnders and Holby City, as Covid-19 spread across the UK.
