Gain Theory elevated Manjiry Tamhane to worldwide CEO.

TheStreet named David Callaway as chief executive officer.

Worldwide Partners named John Harris as president and chief executive officer.

Gurucul named Rosanna Pellegrino as vice president of strategic alliances.

Hook named Brandy Cole as associate creative director.

KBS named Patrick Scissons as global chief creative officer, based in New York. Scissons joins the agency from Grey Canada where he most recently served as chief creative officer, overseeing mass consumer, digital and social work for Volvo, Procter & Gamble, Diageo, Brown-Forman, GlaxoSmithKline, Post Foods and Moms Demand Action for Gun Sense in America. He is credited with the branding and launch of Moms Demand Action for Gun Sense in America, an advocacy group founded in December 2012 following the Newtown shooting. Prior to Grey, Scissons founded "Birthplace," a digital agency that was acquired by WPP in 2011. Before …

UK-based digital marketing agency, Jellyfish, promoted Hannah Rainford from senior social and outreach manager to associate director of social media. In her new role, Rainford will oversee the social activity across many of the agency's larger accounts. She will also help grow the agency's social, content and outreach offering in conjunction with the global management team and continue to run social media training courses for Jellyfish Training.

Allen & Gerritsen hired Pete Valle as a group creative director and Marie Rockett as an associate creative director. In addition, Chris Lee was promoted from vice president, creative director to senior vice president, group creative director. Valle joins the agency from Arnold Worldwide, where he worked on the Jack Daniels, Progressive Insurance and Solar City accounts. Prior to Arnold, Valle spent three years as an associate creative director at SapientNitro where he worked on digital campaigns for Chrysler, Ram Trucks, Jeep and Dodge. Rockett previously worked at SapientNitro on cross-channel campaigns for Dunkin Brands, including its partnership with Liverpool …

FCB/Six, the data-driven creative agency formally known as Rivet, a leading data-driven creative agency, hired Ian Mackenzie as executive creative director and Kim Farwell as senior vice president of strategy. Mackenzie previously served as executive creative director at KBS Toronto. Farwell worked at American Express in leadership positions in the UK, Australia, and Hong Kong. She also held consulting and agency roles focused on business-to-business, technology and the financial sectors. In addition, the agency also hired Jacob Ciesielski as vice president, data and technology; Vicki Waschkowski as vice president, group account director and Krystle Mullin as associate creative director. "Attracting …

Kelly Johnson was promoted from managing director to president of San Francisco-based twofifteenmccann, a unit of McCann Worldgroup. Johnson joined the agency three years ago, and has helped expand the agency's client roster to include Hulu, Workday, Machine Zone and Lookout. She joined twofifteenmccann with 15 years of experience in account management, most recently working at Goodby, Silverstein & Partners. "Kelly believes as strongly as anyone in the power of creativity to help brands make a difference. So she's a natural fit in so many ways here," said Scott Duchon, founder and chief creative officer of twofifteenmccann.