DDB Worldwide has appointed Coca-Cola marketing veteran Wendy Clark to serve as president and CEO of North America, effective January 2016.

Ms. Clark, most recently Coca-Cola's president of sparkling brands and strategic marketing in North America, will succeed Mark O'Brien, who will take on the position of exec VP at DDB parent company Omnicom Group.

Mr. O'Brien will work on operational development for some Omnicom businesses in the newly created position, said Chuck Brymer, CEO of DDB Worldwide. Mr. O'Brien will report to Omnicom exec VP-CFO Philip Angelastro.

Having lived in Atlanta since joining Coca-Cola in 2008, Ms. Clark will relocate to DDB's New York headquarters next year.

Mr. Brymer, who has known Ms. Clark for more than a decade, said she's an innovator, as well as an outstanding leader and major figure in both the business and marketing worlds.

"In her role right now [at Coke], she's managing a number of very visual and important brands, and she's dealing with not only the traditional media platforms, but an array of innovative techniques and tools to drive engagement with customers, so she brings a wealth of experience and an understanding of the changing needs of our industry," added Mr. Brymer.

In a memo sent to Coca-Cola employees, Sandy Douglas, president of Coca-Cola North America, said the company will name a successor soon, noting she's "built a talented team and a deep bench of Coca-Cola North America marketers who are ready to assume their place as our next generation of brand leaders."

"Wendy's impact on our business has been significant. Over the course of her seven-year tenure with us, she has guided our global and North America marketing teams. Under her direction, many of our brands found their voice and an authentic presence in the social and digital world. Through it all, she has been an inspiring ambassador for our flagship brand," he said in the memo. "She and her team have created some of our company's most innovative and engaging campaigns, including the global rollout of Share a Coke and the 2014 FIFA World Cup campaign, which spanned more than 175 countries."

In addition to her client-side experience, Ms. Clark, one of Ad Age's Women to Watch in 2007, also brings expertise on the agency side, having worked at GSD&M earlier in her career. She has also served as a board member of the Association of National Advertisers, is an inductee to the American Advertising Federation's Advertising Hall of Achievement and recieved a Matrix Award from New York Women in Communications in 2014.

"A lot of people say the agency world is under pressure and seeing her coming across from her side of the desk speaks volumes, not only as a vote of confidence for the agency business, but for what we're doing at DDB," said Mr. Brymer.

Some of DDB's current clients include Unilever, Mars, Johnson & Johnson, ExxonMobil and McDonald's.

Ms. Clark will be the highest-ranking woman for DDB in the U.S., Mr. Brymer said, noting the management team in Canada is also led by women. Mr. Douglas noted Ms. Clark's dedication to women's leadership initiatives in the memo.

In April, Ms. Clark returned to Coca-Cola after a three-month leave for a personal project. While the beverage giant did not disclose details about the nature of her project, it was widely reported that she was working in some capacity for presidential hopeful Hillary Clinton.

Ms. Clark joined Coca-Cola in 2008 as global head of integrated marketing and communications after serving as senior VP-advertising at AT&T. While at AT&T, Ms. Clark steered that brand through a rebranding and was credited with helping the telecommunications giant navigate a slew of complex acquisitions.

In 2013, Ms. Clark was promoted to lead a new Global Sparkling Brand Center at Coca-Cola. A year later she took on the North American role, while Katie Bayne, who had been president-North American Brands, moved to the global role vacated by Ms. Clark.

Major changes came to Coke's marketing leadership late last year when global CMO Joe Tripodi -- who had hired Ms. Clark -- departed and was replaced by Marcos de Quinto, previously the president of Coke's Iberia business unit.

In March, while Ms. Clark was on leave, Coca-Cola launched a global creative agency review. The review concluded in August when the company tapped three WPP agencies to lead its next big global campaign for brand Coke: Ogilvy New York; Sra Rushmore of Madrid; and Santo of Buenos Aires. The new campaign has yet to hit the market. While Coke has not discussed the new creative direction of the effort, it is possible that "Open Happiness," which debuted in 2009, during Ms. Clark's tenure, could be shelved.