Eric Steinhauser, executive vice president and executive creative director on the agency's Merrill Lynch account, will succeed Mr. Campbell as executive creative director.
Matt Whitten, a freelance creative director, becomes deputy creative director for the Manhattan office. Messrs. Steinhauser and Whitten are expected to partner with the agency's new president, Rosemarie Ryan.
$1.4 billion in billings
The 125-person creative agency, part of WPP Group, handles $1.4 billion in billings, according to JWT.
"I think I've done a good job there and three years is probably enough," said Mr. Campbell when reached at his country home. "I always told people I was a cartoonist that took a full-time job until cartooning took off."
Mr. Campbell said he offered his resignation to Bob Jeffrey, JWT's North American president, last night after mulling over the move during the holidays. "When I came back, I decided it was the right time."