Longtime Warner Bros. Animation President Sam Register Departing

Sam Register, the long-serving head of Warner Bros. Animation , is leaving the studio in a move that even his boss, Channing Dungey, acknowledged was unexpected.

In a memo to staff Tuesday afternoon, Dungey — chairman and CEO of Warner Bros. Television Group and WBD U.S. Networks — wrote that “I know this comes as a surprise and you have a lot to digest.” The memo says that Dungey and Register “mutually agreed” not to renew Register’s contract as president of WB Animation, Cartoon Network Studios and Hanna-Barbera Studios Europe, which was coming to an end.

“It’s time for me to move onto the next chapter in my life, and I’m grateful to have Channing’s support as I exit Warner Bros Animation,” Register said. “It’s been an amazing ride and I want to extend my sincere thanks to all the great people I’ve worked with — we’ve built some incredible things together. I wish you all the best moving forward, and I’m excited to explore all the possibilities in my future.”