Helen Andrews, chief executive of Adam & Eve/DDB, is leaving her post after four months.
She took over as CEO from Tammy Einav, who was named executive chair, in June.
At the time, the agency explained that Einav will “remain heavily involved” in the agency including new business, as well as the wider network and industry initiatives.
Andrews said: “Deciding to leave Adam & Eve/DDB wasn’t an easy decision to make, and I’d like to wish the wonderful team there all the best for the future.”
Adam & Eve/DDB is one of Britain's biggest ad agencies, ranked fourth by billings in the Campaign School Reports 2023, after dropping from first place a year earlier.
Before her time at Adam & Eve/DDB, Andrews worked at Wieden & Kennedy London between 2008 and 2022. Before this, she was at M&C Saatchi for more than seven years.
Einav said: “We’re grateful to Helen for her time at the agency and are sorry to see her go. We wish her well in the future.
“We have a very deep bench of management at A&E/DDB that will continue to lead the agency and look after our incredible people and clients. We will appoint and announce Helen’s successor in due course.”
The agency counts CALM, Lloyds Banking Group, Marmite and Playstation among its clients and was the most awarded UK agency at Cannes Lions 2023 and at the Campaign Big Awards 2022.
Einav and her team made a landmark decision to split with its most famous client, John Lewis Partnership, in February after 14 years, when the retailer put the account up for review.