Anomaly London partner and executive creative director Oli Beale has departed the agency after six years.
Beale said he is leaving to pursue writing for film and television. Anomaly has no plans to replace him.
Joe Corcoran will continue as head of creative, a role he has held for the past two years.
Anomaly founding partner and executive chairman Carl Johnson said: "Oli is a special character who has committed himself to establishing a very strong department and he has earned the right to follow his passions – I fully expect him to triumph and wouldn’t be at all surprised if one day we co-produced his new award-winning show for Netflix!
"Joe is a proven talent and leader at Anomaly and so it should all be very smooth."
Beale added: "After six glorious years, going from 11 people to over a hundred, I’m moving on to a new adventure. I’m proud as a python of the work we’ve done and I’m leaving on a mega-high with this year’s work. I love the creative department harder than a diamond saxophone.
"Advertising is a whole world of fun, but the thing I love most is film and TV. I’ve just turned 40 and if I don’t have a go at breaking into that world now, then I never will."