Mr. Forsyth was part of the London start-up at its launch in 2008, and through its sale to Omnicom Group and merger with DDB London in 2012. His next move will not be until 2018, in accordance with the founders' contracts.
In a statement, Mr. Forsyth said, "I am so proud of what James, David, Ben and I have created at Adam & Eve DDB. It is a fantastic, world-class, creative company with lots of great opportunities ahead. However, I feel it is the right time for me to pursue a new venture."
The remaining three founders have confirmed that they will stay to take on group roles, following the end of their earnout in December 2016. James Murphy is group CEO, David Golding is group chief strategy officer, and Ben Priest is group chief creative officer. The founders promoted a new generation of management in December 2016.
In November the agency opened a New York office to work with Samsung in North America. In the U.K., its offering has expanded to include a content division, Cain & Abel, which grew revenues by 60% last year, while revenues at the agency as a whole grew 16.5%.
Adam & Eve DDB, which was also Ad Age's International Agency of the Year in 2015, has won seven Grand Prix at the Cannes International Festival of Creativity. It is best known for its work for retailers John Lewis, Harvey Nichols and H&M, and recently created a Super Bowl spot for Skittles.