For six seasons, Hilarie Burton played Peyton Sawyer, the female lead on “One Tree Hill,” a Warner Bros. teen drama created by Mark Schwahn. For the first two seasons, Burton said, she struggled against Schwahn’s efforts to gratuitously sexualize her character — fights that earned her a reputation for being “difficult.”

But after the show’s second season, according to Burton, inappropriate behavior by Schwahn that she and her costars dismissed as social awkwardness grew more intense.

“Things took a turn in season three,” Burton said. “That’s when Mark decided that I was his muse.”

Speaking to Variety, Burton recalled years of harassment and assault that she alleges Schwahn perpetrated against her and other women on the show. She claimed that Schwahn twice forced himself on her, kissing her on the mouth without warning and against her will. She said Schwahn touched her inappropriately while in the presence of his wife. All in all, she described a culture on “One Tree Hill” in which Schwahn pitted women against each other, was verbally abusive, and spread false rumors about physical relationships he claimed to have had with female cast members.

She is not alone. A former writer on the show, Michelle Furtney-Goodman, recalled to Variety an incident in which Schwahn, in front of the show’s writing staff, forced her head down between her knees, balanced a soda can on her, and joked about her performing oral sex. Another female actor, speaking anonymously, described pushing Schwahn away after he grabbed her suddenly and pulled her between his thighs. The alleged incident occurred on set, in front of crew.

A representative for Schwahn declined to comment on the record for this story.

Schwahn was suspended Wednesday from his current job, as showrunner on E! drama “The Royals,” which he also created. The suspension came two days after Burton and 17 other women sent a signed letter to Variety accusing Schwahn of sexual harassment. That letter was prompted by a Twitter thread that “One Tree Hill” season seven writer Audrey Wauchope posted Nov. 11.

In the Twitter thread, Wauchope described being subjected to frequent and unwanted touching by a male showrunner she had worked for; seeing him display naked photos of an actress that he was having a sexual relationship with to staffers without the actress’ knowledge; and calling Wauchope’s writing partner into his office to try to talk her out of getting married and into dating him.

Wauchope did not identify Schwahn by name. But as multiple women who worked on “One Tree Hill” began tweeting their support for her — including several actresses such as Burton, Sophia Bush, and Bethany Joy Lenz — it became obvious that the showrunner she had written about was Schwahn.

Wauchope decided to share her experience after reading a report by Variety’s Maureen Ryan detailing alleged sexual harassment by “Arrow” and “Flash” showrunner Andrew Kreisberg. She did not expect to attract much attention.

“I never thought that anyone would read that and that it would turn into this,” she told Variety. “I was just trying to explain why these staff jobs can be so toxic if you have a showrunner who is an abuser or a harasser.”

Within a day of her initial Twitter posts, the show’s female cast members began texting each other, formulating a plan for a joint response and show of support. Wauchope and other writers came on board, and the letter was published Nov. 12.

“Many of us were, to varying degrees, manipulated psychologically and emotionally. More than one of us is still in treatment for post-traumatic stress,” the cast and crew wrote in the letter. “Many of us were put in uncomfortable positions and had to swiftly learn to fight back, sometimes physically, because it was made clear to us that the supervisors in the room were not the protectors they were supposed to be. Many of us were spoken to in ways that ran the spectrum from deeply upsetting, to traumatizing, to downright illegal. And a few of us were put in positions where we felt physically unsafe.”

In an interview with Variety the day after the letter was published, Burton described in detail her experience working with Schwahn, who was showrunner on all nine seasons of the series — which aired first on the WB, then the CW. A former MTV veejay, Burton said Schwahn positioned himself as a mentor; pushing her character to the forefront, allowing her to sit in on production meetings, and offering support for her dream of starting a record label. “I realize now that I was being groomed as bait,” she said.

Burton described a pattern of behavior in which Schwahn would allegedly manipulate female cast members by playing them against each other — and that he would often encourage new female actors on the show to develop social relationships with Burton as a way to draw them into his orbit. Actress Danneel Ackles, who joined the series in season three, said that Schwahn encouraged her to develop a friendship with Burton, telling Ackles (née Harris), “Hilarie’s one of the good guys. Hang out with her.”

Burton said that she received multiple late-night phone calls from Schwahn during production of season three in which Schwahn, who was married, tearfully declared his love for Ackles, with whom he claimed to be having a physical relationship. (Ackles told Variety that she never had such a relationship with Schwahn.) Burton said that, on one such phone call, she reprimanded Schwahn and told him that she did not want to be his confidant regarding the alleged affair. The next day, she said, she received flowers with an unsigned note that read “Thank you for being my secret keeper.”

In 2006, Schwahn invited Burton and Ackles to attend an outdoor concert with him and his wife. “I thought, ‘Oh, well, his wife’s coming,” Burton said. “Great. Maybe there’s nothing going on and I’m being paranoid.” But at the show, Burton said, Schwahn, with one arm around his wife, put the hand of his other arm on the small of Burton’s back and slid his hand beneath the waistband of her pants. Burton said that she eventually excused herself to get a drink. Ackles confirmed that she saw Schwahn slide his hand into Burton’s pants.

For season four, Warner Bros. Television held a contest in which high school students nationwide vied to host the production of an episode of “One Tree Hill.” Burton and Schwahn traveled together to Honey Grove, Texas, to announce that the town would serve as a season-four location. The two traveled back to the production’s permanent home in Wilmington, N.C. together — taking a flight from Texas to Raleigh, N.C., then a roughly two-hour limo ride from Raleigh to Wilmington.

It was during the limo ride that Schwahn first allegedly forced himself on Burton.

Schwahn, according to Burton, said that he was about to call CW president Dawn Ostroff and pitch her an idea in which season five would pick up five years after the end of season four. Knowing Burton’s desire to produce, he would allow her to listen in on the call. Burton sat on the opposite side of the limo’s passenger cabin as Schwahn explained the idea to Ostroff. After a few minutes, Schwahn motioned for Burton to sit next to him and listen in, which she did.

“I’m leaning in listening, and when it’s Dawn Ostroff’s turn to talk, he just leans over and starts kissing me,” Burton said. “I push him off, but I can’t say anything, because he’s on the phone fighting for our show to stay on the air. I’m just in this position where I’m thinking, ‘You’ve got to take it, Hil. Just laugh it off. You’ll get to Wilmington in 45 minutes.’”

According to Ackles, Schwahn, after arriving on set that day, approached Ackles and told her that he and Burton had “made out” on the limo ride from Raleigh. Ackles called Burton, who told her about the incident on the phone call with Ostroff.

A few weeks after the trip to Texas, Burton received an invitation from Schwahn to “the kissing club.” A note arrived at Burton’s residence, she said, sealed in a black lipstick kiss, inviting her to meet Schwahn at 9 p.m. at Deluxe, a local restaurant. “He had this grand idea that it was going to be this swingers make-out club where people who are in relationships can make out with no strings attached,” she said. Burton, who was living at the time with a boyfriend who was a crew member on the show, did not go to the meeting.

“There was no way I was going to go,” she said. “So I stood him up, and he was pretty angry about it.”

In February 2007, the bulk of the crew and cast went to Texas to shoot the contest episode. After the episode wrapped, Schwahn arrived late to a party attended by Burton and several cast and crew members at a local bar. That’s when he allegedly forced himself on her for the second time.

“I’m at the bar waiting to get drinks for the hairdresser and me, and he leans over and he kisses me in front of everybody,” she said. “Right on the mouth. It was something I had to get out of. It wasn’t a peck. It wasn’t ‘Hey, sis, how’s your day?’ It was a boyfriend kiss.”

Another actress who worked on the series told Variety that Burton told her about the incidents in the limo and at the party in Texas, neither of which she was present at.

The same actress, who asked not to be named in this story, told Variety that during season one, she approached Schwahn on set with a question about her sides. Schwahn, she said, put his arm around her, ran his hand from her upper back to the small of her back, then pulled her in between his legs. The actress said that she then hit Schwahn in the chest, told him not to touch her that way, and returned to her question.

The same actress said that when she later told Schwahn that he should stop touching the actresses on set, he threatened her job.

In season 4, Schwahn and several members of the cast traveled to Miami for an event that was part of a sponsorship deal between the show and Sunkist. Ackles said that during the trip, Schwahn, after calling her phone more than 10 times, came to her hotel room in the evening and began knocking on the door for several minutes, asking to be let in. Ackles said that she did not answer, but that Schwahn continued to knock and that she eventually exited to the room’s balcony, until he stopped knocking and left.

According to Burton, Schwahn came to her room shortly thereafter. She opened the door and Schwahn entered, she said, and began complaining that Ackles would not open her door for him.

During shooting of the season-four finale, Burton said, Schwahn approached her from behind and began rubbing her shoulders, then her back.

Burton said that she wheeled around and told Schwahn, “You gotta stop. Mark, I’m telling you, as your friend, your wife is going to hear about this shit. You’re going to lose your job. You can’t touch the girls anymore.”

Schwahn, she said, “was furious. I guess other people maybe heard it. I had reprimanded him in front of people. And that’s unforgivable.” Early the next morning, after shooting had wrapped, Schwahn ordered her into his office, and, according to Burton, screamed at her for half an hour. “He went crazy,” she said, adding, “I know exactly what this man’s hands look like, and they are my fucking nightmare. I think of hands when I think of him, because they were relentless.”

Burton — now in a recurring role on another Warner Bros. series, Fox’s “Lethal Weapon” — left “One Tree Hill” after her contract ran out at the end of season six. She said that she turned down a substantial raise from Warner Bros. Television to return for season seven, but did not speak to anyone at Warner Bros. about Schwahn’s alleged inappropriate behavior. “I didn’t want Warner Bros. to view me as a problem, because they had been so supportive” she said. “I wanted to work at Warner Bros. again. I’m working at Warner Bros. now.”

Ackles left the show in season five. On her last day in Wilmington, she said, Schwahn appeared outside her apartment in the early morning as she prepared to fly to Los Angeles to begin shooting the feature “Harold & Kumar Escape From Guantanamo Bay.” “Mark Schwahn is standing outside my apartment — would not leave, wants to say goodbye, wants one last hug, would not get in his car,” she said. “I could not go outside and get in my car, because he wouldn’t leave.” Schwahn left, she said, after she told him through an intercom that she would call the police if he did not.

Ackles returned to the show for multiple episodes in season seven. She said that she agreed to return in part because the proposed storyline would see her character married to Paul Johansson, an older actor on the series. “He would never do anything like that in front of Paul,” she said.

As showrunner, Schwahn split time between Wilmington and the show’s office in Burbank. Michelle Furtney-Goodman was one of the women who worked in that office. Now head of development for production company Super Delicious, Furtney-Goodman met Schwahn while working as an assistant to WB president Jordan Levin. She became Schwahn’s assistant for season three of “One Tree Hill,” then was promoted to staff writer the following season.

During a writers’ room discussion of the one episode she wrote in season four, she said, Schwahn began rubbing her shoulders. He then moved his fingers into her hair.

“He announced to the room that the back of my head was so flat and that I was the perfect woman, because I could give a guy a blowjob and he could rest his drink on the back of my head,” Furtney-Goodman said. “After that, he proceeded to push my head between my knees and balance a soda can on the back of my head. I remember looking at the carpet and thinking, ‘Oh my god, this is really happening.’”

Furtney-Goodman extricated herself from Schwahn and walked to the front of the room, telling everyone that she needed to look at the white board. She said that she faced the board with her back to the writers “blinking back tears.” She then went to the bathroom, where, she said, “I splashed some water on my face, then went back to work like nothing happened.”

A writer who was present in the room at the time of the incident confirmed Furtney-Goodman’s account. A second writer on the show who was not present in the room at the time said that Furtney-Goodman called her later that day and described the incident to her.

Furtney-Goodman did not report the incident to Warner Bros. “I was scared that if I said anything, I would never work in this town again,” she said.

Wauchope’s writing partner Rachel Specter confirmed that, as Wauchope revealed in her Twitter thread, when Specter asked Schwahn for time off for her wedding, he suggested that she not get married and instead start dating him.

Specter also said that one day in the writers room, Schwahn approached her after she had peeled a strip of gel nail polish off her finger and placed it on the table in front of her. Schwahn, she said, picked the nail-polish strip up and held it in his hand as he spoke about another topic. “I pretended to not notice that he was holding it,” she said. “He continued talking, not missing a beat. Then he opened up his wallet and put it in his wallet behind his license, and put his wallet back in his pocket.”

Another female writer on the show who spoke with Variety, but asked not to be named, said that she was subjected to frequent unwanted and inappropriate touching by Schwahn of her back, hair, and shoulders, and observed him behave in the same way toward other women.

One former male “One Tree Hill” writer, James Stoteraux, told Variety via email that Schwahn gave him as a Christmas present a T-shirt with the words “I’m not a gynecologist, but I’ll take a look” printed on it, and that Schwahn became annoyed when Stoteraux refused to wear it. Stoteraux, who worked on seasons two and three, called the “One Tree Hill” office “a toxic, demoralizing workplace.” When he left the show after season three, he wrote, “I was relieved to be out of there.”

Burton said her experience with Schwahn has had a negative impact on her career. Since leaving “One Tree Hill,” she has refused to audition and refused to work for showrunners she does not already know. She was dropped by her agent after she refused to allow herself to be considered for series-regular roles during pilot season, hesitant to be locked into a longterm contract with a showrunner she didn’t know. (After a period of working with only a manager, she is now represented by APA.)

“The fear of being forced into another one of these situations was crippling,” she said. “I never wanted to be the lead female on any show ever, ever, ever again.”

Representatives for Warner Bros. Television did not respond to requests for comment.

Burton said that she hopes through speaking out, she can affect change in union practices. She said that only once in her nearly two-decade career has she seen a set representative for SAG-AFTRA or its predecessor, Screen Actors Guild. That came while shooting “White Collar” in New York.

“When you’re out on location you can isolate people, and it’s way easier to manipulate people when they’re isolated,” she said. “It would be so important, especially for these location-based shows, where you are away from your agents and your managers and your parents when you’re as young as we were, that you have someone that checks in and just asks basic questions.” Burton suggested that SAG-AFTRA reps should make visits to sets outside of New York and Los Angeles at least every other month.

A SAG-AFTRA representative did not respond to a request for comment.

Schwahn was suspended Wednesday from his new show, E! drama “The Royals,” which he created and served as showrunner on for four seasons. Representatives for E! and “The Royals” producers Universal Cable Productions and Lionsgate Television declined to comment for this story. In a statement Wednesday, E!, UCP, and Lionsgate said that they “take sexual harassment allegations very seriously, investigate them thoroughly and independently, and take appropriate action.”

Hours after Schwahn’s suspension, “The Royals” star Alexandra Park posted a statement on Twitter expressing support for the women who worked on “One Tree Hill.”

“I have a responsibility as someone who was working under Mark Schwahn on ‘The Royals’ to acknowledge these claims,” Park wrote on Twitter. “I am devastated to admit to myself, to my colleagues, and to this industry that I too, have been exposed to this reprehensible behavior.” Her co-star Elizabeth Hurley later posted a statement saying that she “had absolutely no idea” that Park “was feeling frightened and sexually intimidated by Mark.”

On Thursday, Park and Hurley’s colleagues — 25 women who work on the show, actresses and crew members — issued a letter saying, “Despite hearing rumours about his behaviour on ‘One Tree Hill,’ those of us involved from the early stages went into the filming of the pilot hoping they were just that – rumours. By the time we wrapped this had irrevocably proven not to be the case. It became all too apparent reading their statement earlier this week that the betrayal and anger so many of us had experienced during our time on ‘The Royals’ is not exclusively ours. And we were angry then, and we are angry now.”