Robbins' friend and agent Dylan Novak confirmed the news in a statement to USA TODAY Tuesday, sharing that the former child star died by suicide.
"He was a dear friend of mine that I will greatly miss," Novak said. "He was a great friend and the most generous celebrity I’ve ever met. He needed money more than anyone else at the shows he attended, but instead gave away so much free merchandise because he couldn’t stand someone to walk away sad."
Novak added that Robbins "was always very open about... his mental illnesses."
"Every convention we went to, he used his platform to encourage anyone who suffers from mental disorders to get help immediately," Novak said.
As a child, Robbins lent his voice to a slew of Charlie Brown holiday staples, including 1965's "A Charlie Brown Christmas" and 1966's "It's the Great Pumpkin, Charlie Brown." According to IMDb, Robbins was the first actor to voice Charlie Brown, beginning at age nine until he was 13.
Robbins also appeared in a 1964 episode of "The Munsters" and a 1967 episode of "Get Smart" and had a recurring role as Alexander Bumstead on the show "Blondie" from 1968 to 1969. He quit acting in 1972.
In 2015, Robbins faced legal trouble stemming from threatening letters sent to a manager at a mobile home park in suburban Oceanside, California, where he had been living, according to the Associated Press. He also sent letters to members of the media in which he offered to pay money to have San Diego County Sheriff Bill Gore killed.
He was first arrested January 2013 at the U.S.-Mexico border on stalking charges. He later pleaded guilty to stalking an ex-girlfriend and the plastic surgeon who had operated on her. Robbins was sentenced to five years probation but violated its terms and was arrested again.
According to San Diego local affiliate NBC 7, Robbins was prone to outbursts in court. At one of his 2015 court dates, Robbins said he suffered from mental illness.
"This is what happens when you are bipolar. You behave as if you are on drugs," he said in court. "I want justice to be served, but I'm mentally ill."
In a 2019 interview with Fox 5, Robbins encouraged those struggling with mental illness to seek treatment.
“I would recommend to anybody that has bipolar disorder to take it seriously because your life can turn around in a span of a month like it did to me," he said.
If you or someone you know may be struggling with self-harm or suicidal thoughts, you can call the U.S. National Suicide Prevention Lifeline at 800-273-TALK (8255) any time day or night, or chat online.
Crisis Text Line also provides free, 24/7, confidential support via text message to people in crisis when they dial 741741.
Contributing: Andrea Mandell
This article originally appeared on USA TODAY: Peter Robbins, original voice of Charlie Brown in Peanuts, dead at 65