Malcolm Young, the guitarist who co-founded the legendary rock group AC/DC together with his brother, died Saturday at the age of 64. Young had struggled with dementia for the past several years and retired from the band as a result of his illness. He reportedly passed away peacefully surrounded by family. “Today it is with deep heartfelt sadness that AC/DC has to announce the passing of Malcolm Young,” the band announced in a statement. “Malcolm, along with Angus, was the founder and creator of AC/DC. With enormous dedication and commitment he was the driving force behind the band. As a guitarist, songwriter and visionary he was a perfectionist and a unique man,” the statement said. Angus Young, the group's lead guitarist, said his brother leaves behind an “enormous legacy” after the two founded the band together in 1973.