Dushku was among Carpenter's former "Buffy" co-stars, who have supported her since she accused the show's creator, Joss Whedon, of "mean and toxic" behaviour on set last week (ends12Feb21).
And now Charisma feels awful about not backing her fellow actress when she spoke out about workplace misconduct on the set of U.S. series "Bull".
Eliza accused the show's star Michael Weatherly of harassment in 2018 and won a $9.5 million (£6.8 million) settlement from CBS network chiefs after she was fired from the show.
Commenting on Dushku's public post on Instagram, Carpenter wrote, "I owe you an apology. I never lent my voice to you privately nor publicly when you shared your truth after suffering sexual misconduct in the workplace."
"As I wrote to you privately, this makes your statement of support sweeter... your loving embrace empowers others to feel safe to share their stories. Thank you for being who you are. Thank you for your inspiring words of support. I will never forget how you have made me feel."
In her original statement, the actress said, "For nearly two decades, I have held my tongue and even made excuses for certain events that traumatize me to this day. Joss Whedon abused his power on numerous occasions while working together on the sets of Buffy the Vampire Slayer and Angel."
"While he found his misconduct amusing, it only served to intensify my performance anxiety, disempower me, and alienate me from my peers. The disturbing incidents triggered a chronic physical condition from which I still suffer. It is with a beating, heavy heart that I say I coped in isolation and, at times, destructively."
Whedon has still not commented on the accusations.