Lizzie McGuire star Hallie Todd paid tribute to her late costar Robert Carradine after his death. "My heart is broken. I'm going to miss my sweet buddy so much," Todd, 64, captioned a photo of her and Carradine - who died at age 71 following a battle with bipolar disorder - on Tuesday, February 24. "He was a generous and loyal friend. He was brave, strong, kind and had a wicked sense of humor." Todd, who played Lizzie's mom, Jo McGuire, in the Disney Channel series, continued, "He was a champion for the people he loved and always wanted the best for us. He was a wonderful actor, a brilliant guitar player, and the most incredible and devoted father." The actress shared that "over the last 25 years," their "families grew extremely close" and celebrated holidays, birthdays and graduations together. 'Lizzie McGuire' Cast React to Robert Carradine's Death at Age 71 "My friendship with Bobby and his family is probably my most treasured personal gift from working on Lizzie McGuire," she continued. "He was my family on screen and off. My heart, love, strength and prayers are with his family and loved ones as they navigate through this enormous loss." Courtesy of Halle Todd/Instagram Carradine's family announced the actor's death on Monday, February 23. "It is with profound sadness that we must share that our beloved father, grandfather, uncle, and brother Robert Carradine has passed away," they told Deadline in a statement. "In a world that can feel so dark, Bobby was always a beacon of light to everyone around him. We are bereft at the loss of this beautiful soul and want to acknowledge Bobby's valiant struggle against his nearly two-decade battle with bipolar disorder." The statement continued, "We hope his journey can shine a light and encourage addressing the stigma that attaches to mental illness. At this time we ask for the privacy to grieve this unfathomable loss. With gratitude for your understanding and compassion." Carradine's official cause of death has not yet been confirmed. Robert's brother Keith Carradine also told Deadline that his family wanted to shed light on his "valiant struggle" with bipolar disorder. Courtesy of Hilary Duff/Instagram "We want people to know it, and there is no shame in it," he said, noting the illness "got the best of" Robert. "I want to celebrate him for his struggle with it, and celebrate his beautiful soul. He was profoundly gifted, and we will miss him every day. We will take solace in how funny he could be, how wise and utterly accepting and tolerant he was. That's who my baby brother was." Robert and Todd met while filming Lizzie McGuire, which premiered in 2001. Robert starred as Sam McGuire, Lizzie's father. Hilary Duff Reacts to 'Lizzie McGuire' Costar Robert Carradine's Death Hilary Duff, who played Lizzie, also reacted to the actor's death on Tuesday. "This one hurts. It's really hard to face this reality about an old friend," she wrote via Instagram. "There was so much warmth in the McGuire family and I always felt so cared for by my on-screen parents. I'll be forever grateful for that. I'm deeply sad to learn Bobby was suffering. My heart aches for him, his family, and everyone who loved him. 💔."