MEC tapped Kristen Metzger as managing partner, people & culture. She most recently served as executive vice president, managing director of client services at MediaVest.

DDB California hired Jonathan Byrne as creative director. Byrne joins DDB from Venables Bell & Partners, where he spent a decade serving first as a creative and then as a creative director.

Vibrant Media hired Ray Berry as senior vice president of finance.

ThinkVine, a marketing mix optimization solution provider, hired John Hennessy as its executive vice president of sales.

Tremor Video hired Michael Colarossi as national sales director, consumer packaged goods.

Stun Creative has launched Stun Originals, a production startup that will develop original entertainment programming and content for television and the Web. Stun has hired Maria Crenna, former president of Mandeville Television, to run the unit, as president of Stun Originals.

The Online Publishers Association (OPA) hired Jason Kint as CEO, based in D.C. Kint replaces Pam Horan, who was president since 2006. Horan will end her 10-year tenure at the Association on May 30. Kint joins the OPA from CBS Interactive where he was senior vice president and general manager of its Sports division.

JWT Amsterdam hired David Navarro as head of design/interactive director and Agustín Soriano as strategy director.

Meredith Xcelerated Marketing added James Herrera as executive director, user experience.

Andi Sider has joined Cooking Light as integrated account manager and Quinn Nelson was promoted to Midwest manager of sales.