After 15 years with the company, Christina Miller (pictured), the president of WarnerMedia’s Cartoon Network, Adult Swim, Boomerang and TCM will step down at the end of the year.

“This is not a decision I came to lightly,” said Miller in an email to the company. “It’s one of the hardest I’ve had to make in my career. Ultimately, it feels like the right time for me to leave and take a little time to think about what comes next, but I do so, feeling immensely proud of the work we’ve done together and so grateful for the experience.”

Miller has led the kids and young adults division for the past five years, responsible for all aspects of the business, including global oversight of content development, production and franchise management. She also oversees the Boomerang SVOD, which launched in 2018, and was recently given responsibility for TCM.

EVP and CMO for Cartoon Network, Adult Swim and Boomerang, Michael Ouweleen will take over as interim president, while Miller helps the transition.

Her departure from WarnerMedia comes at a time of great transition for the company, since the AT&T-Time Warner merger closed in June 2018, combining the two companies’ media efforts. In March, the company added all kids and YA responsibilities to Kevin Tsujihara’s plate (who was chairman and CEO of Warner Bros at the time). He stepped down shortly after Warner Bros. opened an investigation into a relationship he had with actress Charlotte Kirk, and was replaced in June by Ann Sarnoff.

WarnerMedia has since announced its new SVOD service HBO Max, which will launch next May stacked with content.