Kary Antholis has taken a buyout and will leave the cabler in June. HBO Films president Len Amato will expand his role to include Antholis' duties at Cinemax and overseeing miniseries for the premium cable network.

One of HBO and Cinemax's longest-tenured executives is leaving the premium cable networks.

Kary Antholis, who has served as president of HBO miniseries and Cinemax programming, will depart the company in June. HBO Films president Len Amato will expand his current responsibilities to include Antholis' duties overseeing sibling cabler Cinemax and miniseries.

“I am deeply grateful to HBO for over a quarter century of opportunities to work with many of the world’s great storytellers," Antholis said Tuesday in a statement. "I am particularly pleased that HBO's generosity — in addition to encouraging me to develop and produce TV projects — will allow me to pursue my long-held vision of creating a digital media enterprise focused on crime journalism and storytelling.”

Sources note that Antholis' decision was made before former Showtime and NBC Entertainment head Bob Greenblatt joined new parent company WarnerMedia. The executive — who has been with the cabler for more than 25 years — is said to have been among the staffers who were offered voluntary early retirement packages. Instead, Antholis will focus on new digital opportunities for crime journalism that he had been considering for some time. Antholis will remain as a consultant on projects for the cabler that involve crime and criminal justice as well as a handful of scripted projects.

“Kary has been a key creative force at HBO and Cinemax over the past three decades,” said HBO programming president Casey Bloys. “We are extremely appreciative of all that he has accomplished and contributed to the company, and we look forward to working with him as a producer and innovative voice in his new endeavors.”

Greenblatt was formally confirmed as chairman of WarnerMedia Entertainment on Monday. He will be in charge of WarnerMedia's prized cable networks including HBO, TNT and TBS, as well as its upcoming direct-to-consumer streaming platform. Antholis becomes the latest longtime exec at HBO to exit the company. He joins former HBO chairman and CEO Richard Plepler, who departed last week as rumors swirled around Greenblatt's new role. Greenblatt will take on many of Plepler's responsibilities.

During his tenure, Antholis' credits included The Night Of, Mildred Pierce, Olive Kitteridge, The Pacific, John Adams, Angels in America and the upcoming Chernobyl and Catherine the Great.

The executive also helped Cinemax expand into scripted originals with varying degrees of success with series including Strike Back, Banshee, The Knick and Outcast. The cabler next has scripted fare including Warrior in the pipeline.

For his part, Amato will oversee both films and miniseries as HBO combines the two genres under a single executive last done under former HBO Films president Colin Callender.

“Len has had a distinguished career leading HBO Films to award-winning results,” Bloys said. “He is uniquely qualified to add HBO Miniseries and Cinemax to his responsibilities; and we are thrilled that he will now be overseeing these three areas.”

Added Amato: "Leading HBO Films is one of the great joys of my life and I’m honored to expand my responsibilities to include HBO Miniseries and Cinemax. It’s a privilege to continue working with my colleagues and all the incredible artists who make HBO a very special destination for great talent and whose vision creates such relevant and impactful storytelling."