UPDATED: HBO‘s president and COO Eric Kessler is leaving the company after 27 years. HBO CEO Richard Plepler just made the announcement in a company memo (read it below), highlighting Kessler’s accomplishments that include launching the network’s signature “It’s Not TV. It’s HBO” marketing campaign. The COO position will not be filled as part of executive streamlining. For the time being, Kessler’s reports Rob Roth, Otto Berkes, Shelley Brindle, Pam Levine and Simon Sutton will report to Plepler, with Kessler staying on to help with the transition. The departure leaves Plepler as the sole executive atop HBO with Michael Lombardo as his top lieutenant, capping a six-year transitional period after the 2007 departure of chairman/CEO Chris Albrecht. The initial HBO management structure featured a quintet of top executives: Bill Nelson succeeding Albrecht as HBO chairman/CEO, with Harold Akselrad, Kessler and Plepler as co-presidents, and Lombardo as West Coast president. Akselrad left in 2008 after 25 years at HBO, while Nelson retired last year after a 30-year career at the network. Additionally, Lombardo’s top development executive, Sue Naegle, stepped down as entertainment president last week to segue to a producing deal with HBO.

It is with mixed emotions that I announce that Eric Kessler will be leaving HBO. After careful consideration we have decided that the COO position does not best serve the most effective management process at HBO.

It is important to say that this in no way reflects on the extraordinary talents that Eric has so ably demonstrated in his 27 years at HBO. His accomplishments have helped shape the company throughout its modern history. Eric has been an uncommonly valued colleague and friend to all of us at HBO. While his many contributions could not adequately be reflected here, they are indeed numerous and lasting – in fact, we are currently completing one of our strongest years ever. Eric launched several iconic marketing and advertising campaigns – most notably the award winning “It’s Not TV. It’s HBO” – and his influence is visible on screen through HBO’s lauded on-air promotional efforts. Since 2007, Eric has overseen the distribution of the HBO and Cinemax networks in both domestic and international markets. In addition to the pay television channels, he oversaw the worldwide sale of HBO’s programming through licensing, DVD and digital distribution.

Eric was an early champion of our digital future – he was central in establishing our relationship with iTunes (Apple), driving the exploration of mobile experiences, and ultimately leading the development and worldwide launch of HBO GO. HBO GO is an essential innovation for HBO and without Eric and his team, it would not have emerged as what is widely regarded as television’s most elegant digital product.

Eric’s grace and professionalism are a tribute to his passion and commitment to HBO. He has agreed to work with us during a transition period to ensure continuity. During this period, Rob Roth, Otto Berkes, Shelley Brindle, Pam Levine and Simon Sutton will report to me.

Words are insufficient to express our gratitude, appreciation and respect for a beloved colleague. It is indisputable that he will immediately be inducted into the HBO Hall of Fame.