Veteran Viacom executive Doug Herzog will be leaving his post as President of Music and Entertainment Group in January.

Herzog, who has oversight over several Viacom-owned networks including Comedy Central, MTV and VH1, announced he will be leaving as of Jan. 12 in an internal memo released Wednesday and obtained by Multichannel News. Herzog, who began at his career at Viacom in 1984, would not reveal why he’s leaving the company but said that he had “a helluva run, and I would wish it on anyone. I loved every minute of it.”

The move comes as Viacom continues to undergo changes as it looks to rebuild its struggling cable network brands. Earlier this month, Robert Bakish was named CEO of Viacom shortly after the company pulled out of merger talks with CBS.

During his 25-year tenure, Herzog was responsible for overseeing the launch of several of Viacom’s most popular franchises, including The Daily Show and South Park. Herzog didn't specify what his next move would be but did say in the memo: "I'm looking forward to seeing what the next chapter brings. I'm excited and little uncertain, and that feels about right."

Here is the Herzog’s memo in its entirety:

Hey everyone.  

I have some news to share today. I will be stepping down from my post here at Viacom effective January 12th.

Thus ends a 25 year professional journey, and wild ride spanning seven networks, four decades, three Daily Show hosts, over two separate tours of duty, and one joint venture.

It all started innocently enough in 1984 when I was just 25. I arrived at the midtown MTV offices very early one September morning only to find the lobby completely dark.  Not one light on and not a soul there. Thankfully Judy McGrath arrived soon after the lights went on and showed me to my office.

I was given a front row seat at the center of pop culture and an opportunity to redefine it a few times along the way.  In no time, it seems I was surrounded by a seemingly endless universe of creative geniuses, rock stars, politicians, supermodels, heavyweight champs, comedians, street hustlers, and media moguls. And that was just one night at the VMAs!

We found Jon Stewart in an MTV conference room during a game show run-through, lost Dave Chappelle in South Africa and later found Trevor Noah there, we discovered Matt Stone and Trey Parker on VHS and Pauley Shore in Daytona Beach. (So yeah, that one's on me too.)  At MTV News we impacted a presidential race (legally), I got to pump the hand of a POTUS or two, and laughed out loud when Comedy Central unwittingly roasted a future one. I could do this all day.

Along the way, we launched countless hit shows, staged ground breaking tent pole  events, threw some epic parties all the while establishing a unique creative culture fueling our awesome brands. Most importantly we connected deeply with our audiences in a way no one else ever had.

It was a helluva run, and I would wish it on anyone. I loved every minute of it.

As a new year dawns enormous change and disruption dominate the media landscape and the world at large. I know it can be unsettling. But trust me, you should be excited and invigorated by it. Reinventing the brands and innovating with content are the great core strengths of this company. Bob is already bringing true leadership and vision to Viacom. He is a big believer in the power of these brands across all platforms. I promise you are in very good hands with him, as well as your tremendous brand leaders.

The best ideas and best people win every time, and you have both right here.

And if content is indeed king, and brands its queen, then you represent a powerful kingdom poised to return Viacom where, once more, it will be the envy of its peers.

When I speak to anyone interested in this business, I always tell them: "You gotta work hard, you gotta be smart, you gotta be talented, and you gotta be a little lucky.”

I consider myself a very lucky man.  Lucky to have worked so long at a place filled with amazing and talented people. I leave here enormously proud of everything we accomplished together.

I want to thank all my many great colleagues from over the years, including Tom Freston, Judy and everyone from the original MTV days. And of course the current M&E team: John, Kassie, Tanya, Jason, Kent, Chris, Kevin, Patrick, Whitney, Dave, Dan and Alex. These are some of the finest individuals I have ever had the opportunity to work with. I am so grateful for their friendship, council and support. It means the world to me.

And finally, to all of you at the M&E Group. I want to thank you for everything over the years. I cannot tell you how appreciative I have been for all your hard work, creativity, and support. Your passion for the brands and content inspired and motivated me every day.

I'm not gonna lie, there are so many things I will miss. Like the excitement of seeing a great pilot for the first time, or the thrill of a killer new spot. But mostly I will miss all of you, walking these halls and feeding off the unmistakable energy that defines this culture.  It was my great privilege and honor to lead, collaborate, and create with you for so long. I will never forget it.

Many of you know I am just a camp counselor at heart. I tried to bring a little of that to the workplace every day.  Lead the group, play to win, and have fun doing it. 

For now, I'm looking forward to seeing what the next chapter brings. I'm excited and little uncertain, and that feels about right.

This company has been home to me for a long time. So I will be rooting for all of you, my "homies", from wherever I may be, and wishing you all the best.

So take care of your brands, take care of your franchises, but most importantly, take care of one another. I look forward to seeing you all somewhere down the road. And remember . . .  keep a light on.

Comedy Central has confirmed that network president Michele Ganeless is leaving the network, and original programming president Kent Alterman will step into that role effective immediately.

David Bernath, Comedy Central’s executive VP of programming and multiplatform strategy, has been promoted to general manager. Ganeless will remain on board as an adviser until September.

News of Ganeless' departure leaked a day ahead of the announcement, with some reports tying her departure to the network's falling ratings and comments Viacom CEO Philipe Dauman made recently about a pending revival at Comedy Central.

A network spokesman, however, said the decision "was 100% Michele's choice."

"The coverage has been somewhat inaccurate," he said. "Her contract was up this year, and she made the decision not to stay and to move on to the next chapter in her career."

Ganeless, who was part of the team that launched the network in 1991, and Doug Herzog, president of Viacom Media Networks, Music and Entertainment, officially announced the change Tuesday morning (May 10).

"It has been ... an absolute privilege to help build the cultural force that is Comedy Central today," Ganeless said. "The deep connection I have to it and to so many of my colleagues, especially my dear friend and mentor Doug [Herzog], made this decision incredibly difficult. But after considerable thought, I have decided that the time is right to move on and challenge myself in new ways.”

Ganeless joined Viacom in 1990 and, except for a three-year stint at USA Network (2001-04), has remained there. She became network GM on her return in 2004 and was promoted to network president as well in 2007.

Comedy Central credited Ganeless with steering the network from a linear channel to a multiplatform brand that last year won a network-record eight Emmy Awards (from a total of 26 nominations).

Alterman, who will remain based in Santa Monica, Calif., will report to Herzog; Bernath, based in New York, will report to Alterman.

The new network president, who Comedy Central said was "a key voice in selecting Trevor Noah as the new host of The Daily Show and launching The Nightly Show With Larry Wilmore, had been named original programming president in 2013, three years after rejoining the network in 2010 as head of prgramming and production. He had previously spent four years in development at Comedy Central (1996-2000).

Since 2010, Comedy Central said, Alterman has more than doubled the network's original series, creating and developing hit franchises including Emmy Award-winning series Inside Amy Schumer, @midnight with Chris Hardwick, Drunk History, the Emmy-nominated Key & Peele, Broad City and Workaholics, among others.

MTV opened its glitzy upfront presentation in New York early Thursday evening by recognizing the death of musical icon Prince.

Viacom Music and Entertainment Group president Doug Herzog addressed the large crowd of advertisers and journalists by praising the life and work of Prince, who died suddenly Thursday at the age of 57.

Describing himself as MTV’s oldest employee and its biggest Prince fan, Herzog said the network couldn’t start its upfront without acknowledging the unimaginable passing of “one of the greatest artists in music history.”  

He added that Prince had been synonymous with MTV since the very beginning of both MTV and his career. “Even though we’re still processing the news and remembering the enormity of his legacy, I think it’s clear to remember what he was - -a once in a lifetime artist whose music touched all of us and will be missed dearly by everyone around the world,” Herzog said.  

RELATED:Prince Tribute Specials Continue To Pour In | Upfronts 2016: MTV Turns Up the Volume

MTV Wednesday appointed former Discovery Communications digital executive Sean Atkins as the network’s new president.

Atkins, who replaces former MTV president Stephen Friedman -- who announced his decision to leave the company hours earlier -- will oversee all creative and business operations for the youth-targeted network as well as its sister networks MTV2 and mtvU, said MTV officials. 

Most recently, Atkins served as general manager and executive vice president of digital media and strategy for Discovery, where he was responsible for driving the company’s original online video strategy and networks including Revision3, SourceFed, Discovery News, and TestTube, said MTV.  

Atkins will report to Doug Herzog, President of the Viacom Music and Entertainment Group. MTV Executive Vice President and Head of Scripted Development Mina Lefevre and Head of Reality Programming and Executive Vice President of Series Development Lauren Dolgen will report directly to Atkins. 

“Sean is smart, creative, passionate, and remarkably energized about the sea change at hand in our industry,” said Herzog in a statement. “The strength of MTV lies in its ability to constantly reinvent, and Sean’s forward-thinking, versatile leadership will ensure our brand and business continue to evolve and deliver for our audience.”