Michelle Trachtenberg says Joss Whedon was not allowed to be alone with her on the 'Buffy the Vampire' set

• The "Buffy" star spoke about the on-set rule in an Instagram post.
• It follows costar Charisma Carpenter alleging that Whedon "abused his power on numerous occasions."
• Sarah Michelle Gellar has spoken in defense of Carpenter.

Michelle Trachtenberg has given a "last" comment about her experience on the "Buffy the Vampire" set with its creator Joss Whedon.

On Thursday, the actress (who played Dawn Summers on the show) claimed that there was a rule on set that Whedon was not allowed to be in a room alone with her.

"The last. Comment I will make on this. Was. There was a rule. Saying. He's not allowed in a room alone with Michelle again," Trachtenberg wrote in an Instagram post. In the same post, Trachtenberg had reposted "Buffy" star Sarah Michelle Gellar's social media post saying she "stands with all survivors of abuse and am proud of them for speaking out."

Insider contacted Whedon's and Trachtenberg's representatives for further comment but did not get a response.

Trachtenberg originally shared Gellar's post with the caption "I am brave enough now as a 35 year old woman... To repost this," she wrote. "Because. This must. Be known. As a teenager. With his not appropriate behavior....very. Not. Appropriate. So now. People know. What Joss. Did."

She later edited the caption and added the part about the on-set rule.

Stories of Whedon's on-set behavior first made news on Wednesday when her "Buffy" costar Charisma Carpenter took to her social media with a lengthy statement claiming Whedon "abused his power on numerous occasions" while she worked for him on "Buffy" and the spin-off series "Angel."

Looking back on her experience, Carpenter wrote, "the disturbing incidents triggered a chronic physical condition from which I still suffer."

"Like his ongoing, passive-aggressive threats to fire me, which wreak havoc on a young actor's self-esteem," Carpenter wrote. "And callously calling me 'fat' to my colleagues when I was 4 months pregnant, weighing 126 lbs. He was mean and biting, disparaging about others openly, and often played favorites, pitting people against one another to compete and vie for his attention and approval."

Carpenter also claims that when she was pregnant, Whedon "asked me if I was 'going to keep it' and manipulatively weaponized my womanhood and faith against me."

The latest "Buffy" star to come out and support Carpenter is Eliza Dushku who on Thursday wrote on her Instagram: "CC, my heart aches for you and I'm so sorry you have held this for so long," she wrote. "Your post was powerful, painful, and painted a picture we'll collectively never un-see or un-know."

Along with being the creator of "Buffy" and "Angel," Whedon also directed the first two Marvel "Avengers" movies, 2012's "The Avengers" and 2015's "Avengers: Age of Ultron," and directed the reshoots of 2017's "Justice League" after Zack Snyder exited.

It was following "Justice League" that Whedon's alleged bad behavior on set was first publicly discussed when Ray Fisher, who played Cyborg in the movie, spoke out last year against Whedon's treatment of the cast and crew on the movie saying it was "gross, abusive, unprofessional, and completely unacceptable."

The claims have since been backed up by Jason Momoa, who played Aquaman in the movie and said the cast was treated "s---ty" during reshoots. Gal Gadot, who plays Wonder Woman, also has said that her experience with Whedon on the movie "wasn't the best."