Y&R global CEO Hamish McLennan made the announcement today. Marsh is taking a break to write his third book.
"We are sorry to see Nigel go. We will miss his clarity, enthusiasm, strategic skills and his unfailing honesty," said McLennan.
Howcroft will replace Marsh from his role as national CEO of George Patterson Y&R in the coming months.
"It will be a seamless transition. Russel and his team have done a great job in rebuilding George Patterson Y&R and he is the logical choice to take over the Y&R Brands role," says McLennan.
Howcroft said Marsh has been an outstanding motivator for the Y&R Brands team. He adds the company is currently in great shape and he looks forward to building on the group's success.