Herb Scannell already has a book-worth of chapters in media including a decade-long tenure running Nickelodeon and, later, founding one of the first major digital video platforms, Next New Networks, sold to YouTube in 2011. Today he announced that he plans a new one. He will end his five-year tenure as President of BBC Worldwide North America in August, turning the reins over to Ann Sarnoff, the operation’s COO.

“After five years, and with a strong leadership team in place, it feels like the right time for me to return to the entrepreneurial path I was on in digital media before I joined BBC Worldwide,” Scannell says. His relationship with Sarnoff, which goes back to their days at Viacom, has been “one of the most fruitful partnerships of my career. Ann will take BBC Worldwide to new places.”

BBC says that during his tenure Scannell helped to drive a 50% increase in revenues, boosted BBC.com and developed BBC Worldwide Productions — the Los Angeles-based production operation whose productions include ABC’s Dancing With The Stars. The exec also built BBC America, leading to its joint venture last year with AMC Networks.

BBC Worldwide CEO Tim Davie calls Scannell “a visionary and passionate executive who has rapidly grown and fundamentally transformed the North American business.” He also lauded Sarnoff, describing as “Herb’s collaborative partner” who brings “solid strategic and creative business sense.”

Doctor WhoSince joining in 2010, she has overseen most of the North American operation’s revenue streams including home entertainment and licensing and helped to build franchises including Doctor Who, Top Gear and BBC Earth. Deals with cable and satellite companies increased BBC America’s distribution to 80 million from 68 million.

Sarnoff says that she will “build upon the growth trajectory that we’ve achieved under Herb’s leadership” and “leverage the power of the BBC brand and the rich assets we have to grow across platforms.”