Hayden Panettiere, an actress known for her roles on the NBC series "Heroes" and the musical drama "Nashville," has died at the age of 36. Her representatives announced her passing on Sunday, stating, "It is with profound sadness that we share the tragic passing of our beloved Hayden." The cause of her death was not immediately disclosed.

Panettiere's final Instagram post, shared two weeks prior to her death, featured a black and white photo of her with director and photographer friend Randall Slavin. The caption read, "Good times and good friends @randallslavin ✨." Following news of her death, Slavin paid tribute on his Instagram Stories with the message, "Peace be with you, H."

Other notable figures in entertainment also shared their grief. Actress Selma Blair wrote on Instagram, "I love you. Don't be gone. Don't be gone. Please. Please." Melissa Barrera posted to her Instagram story, "Rest in peace sweet Hayden." SAG-AFTRA issued a statement mourning "the sudden passing of Hayden Panettiere."

Panettiere, who was set to turn 37 on Friday, was remembered by colleagues as an "incredible light and a force of nature." Her career began in her youth, with early roles in the ABC soap opera "One Life to Live" and the CBS soap opera "Guiding Light." She gained wider recognition for her role as cheerleader Claire Bennet in the 2006 series "Heroes," which centered on the mantra "Save the cheerleader, save the world." For this role, she won three Teen Choice Awards.

She later achieved further acclaim as Juliette Barnes in "Nashville," a role for which she performed her own singing and earned two supporting actress Golden Globe nominations. During the show's run, 11 of her songs appeared on Billboard's Hot Country Songs charts.

Panettiere, known for her roles on the hit series Heroes and drama Nashville, was remembered as 'an incredible light and a force of nature' as her death was announced over the weekend

Beyond these prominent roles, Panettiere appeared in the "Scream" franchise as Kirby Reed and lent her voice to video games such as "Until Dawn" and "Kingdom Hearts." Her other acting credits include "Remember the Titans," "Ally McBeal," and "Ice Princess."

In recent years, Panettiere had been open about her struggles. Her memoir, "This is Me: A Reckoning," became a New York Times best-seller. In it, she detailed her experiences with drug addiction, which began at age 15, and postpartum depression following the birth of her daughter, Kaya, in 2014. She shared that she had been sober in recent years, describing sobriety as an "everyday battle" and "an everyday choice."

Panettiere also discussed relinquishing custody of her daughter to ex-partner Wladimir Klitschko in 2018, citing her struggles with postpartum depression. Her daughter currently resides in Europe.

Panettiere was also predeceased by her brother, Jansen, who died in February 2023 at the age of 28.

Law enforcement sources confirmed to TMZ that police responded to an incident involving the actress, and an investigation is ongoing. Representatives stated that more information would be available soon. Sources also told TMZ that Panettiere had recently complained of back pain and had traveled from Los Angeles to the South with her boyfriend, Brian Hickerson, shortly before her death.