Arleen Sorkin, who voiced Harley Quinn across the animated DC Universe, has died aged 67.
The actress's death was confirmed to Fox News on Sunday by a representative for her's husband - Modern Family co-creator Christopher Lloyd.
Guardians of the Galaxy director and DC co-head James Gunn paid tribute to the late actress.
"Rest in Peace, Arleen Sorkin, the incredibly talented original voice of Harley Quinn, who helped to create the character so many of us love," he shared to Instagram on Sunday. "Love to her family and friends."
Mark Hamill, who starred opposite Arleen as the Joker in Batman: The Animated Series, also took to social media to express his condolences.
"Devastated to learn we've lost the brilliant Arleen Sorkin," the Return of the Jedi star wrote on X/Twitter. "Not just a wonderful talent, but a truly wonderful person. I'm grateful not only to have worked with her, but to have been her friend. Sending my heartfelt condolences to her family & loved ones."
Arleen's acting career began in the 1980s with uncredited roles on Saturday Night Live and Trading Places, before landing the role of Calliope Jones in Days of Our Lives in 1984.
The actress also voiced Harley Quinn in a number of animated classics, including Batman: The Animated Series, Justice League and Batman: Arkham Asylum.
Actress Tara Strong succeeded Arleen as the voice of Harley Quinn, while Kaley Cuoco was cast as the character in the new animated series.
The DC character skyrocketed to fame after Margot Robbie portrayed the anti-hero in 2016's Suicide Squad.