From surprise resignations to a sex scandal, WarnerMedia's leadership has undergone a major shakeup since AT&T took over

Tsujihara was allegedly involved in a sexual relationship with actress Charlotte Kirk and promised to get her acting roles, according to a report from The Hollywood Reporter (Kirk has denied that the relationship impacted her casting, and has said that the relationship ended many years ago).

"It is in the best interest of WarnerMedia, Warner Bros., our employees and our partners for Kevin to step down as Chairman and CEO of Warner Bros.," WarnerMedia CEO John Stankey said in a statement on Monday. "Kevin has contributed greatly to the studio's success over the past 25 years and for that we thank him. Kevin acknowledges that his mistakes are inconsistent with the Company's leadership expectations and could impact the Company's ability to execute going forward."

Tsujihara was the first person of Asian descent to be the head of a major movie studio, and was in the role since 2013. He joined Warner Bros. in 1994 as the director of special projects finance. Prior to being named CEO, he was the president of Warner Bros. Home Entertainment.

WarnerMedia is continuing its investigation of Tsujihara with outside counsel and said he was cooperating.

Plepler unexpectedly resigned from his role of CEO of WarnerMedia's premium cable network, HBO, last month. A replacement has not been chosen.

"Hard as it is to think about leaving the company I love, and the people I love in it, it is the right time for me to do so," he wrote in a memo to staff. "In the past weeks, I've thought a lot about the incredible journey of this company in the nearly 28 years that I have been blessed to be here. It's a journey of great pride and accomplishment because so many of you, and many others before us, have made HBO a cultural and business phenomenon."

Plepler joined HBO in 1992, and became CEO in 2012 after serving as the network's co-president.

Under Plepler, HBO continued its awards dominance, carrying its prestige status with Emmy-winning shows like "Game of Thrones," "Big Little Lies," and "Barry." The network always prided itself on quality over quantity, focusing heavily on a stacked Sunday night lineup.

But AT&T was quick to make its intentions for HBO known. The company wants to increase the amount of content HBO develops in an effort to compete with Netflix. Plans are in motion for two hours of primetime original programming on Monday nights along with Sundays, and AT&T is expected to launch its own streaming service this year that will include HBO.

"It's not hours a week, and it's not hours a month," WarnerMedia CEO John Stankey said in July. "We need hours a day. You are competing with devices that sit in people's hands that capture their attention every 15 minutes. I want more hours of engagement."

Martin was previously CFO of Time Warner and became CEO of Turner in 2014 after being handpicked by former Time Warner CEO Jeff Bewkes, according to Deadline. He immediately stepped down once the Time Warner/AT&T deal closed in June.

"You’ll note that we have changed how Turner is organized given that John Martin will no longer be with the company as a result of the merger," Stankey wrote in a memo to staff in June. "This initial Turner org structure will allow me to work more closely with more Turner leaders and accelerate my personal learning of the business as we define our shared priorities across the company."

Martin was a top candidate to succeed Bewkes before he resigned, according to Recode.

Levy announced earlier this month that he was stepping down as president of Turner as AT&T continues to restructure Time Warner.

"I have spent a considerable amount of time during the past few months discussing the future landscape and vision of the company with John Stankey and the senior leadership team," Levy wrote in a memo to staff on March 1. "After much consideration and more than 32 years at Turner, the past six years as the President of this great company, I have decided the time is right to leave my role."

Levy oversaw the cable networks TBS, TNT, Cartoon Network, Adult Swim, Boomerang, truTV, and Turner Classic Movies. He also oversaw the company's sports rights deals.

Amid speculation that AT&T wanted to combine Turner and HBO and put former NBC exec Bob Greenblatt in charge (he was later hired for WarnerMedia's top content role), Levy and former HBO CEO Richard Plepler were becoming agitated with the changes, according to Variety, who cited an anonymous, "high-ranking" source at WarnerMedia.

"It says to me, Turner is going to undergo a significant restructure," an insider told Business Insider after Levy's resignation.

"Dave was a big, bold presence and a public face," another said. "Who replaces him in sports, where he's beloved?"