Robert Carradine, the actor known for appearing in the Disney series “Lizzie McGuire,” has died, his family confirmed Tuesday.

He was 71.

His manager Keith Carradine, also his brother, said in a statement that the actor had “succumbed to bipolar disorder after fighting it for almost 20 years.”

Hilary Duff, who played Lizzie McGuire alongside Carradine as her on-screen dad, was among those to pay tribute to him.

“This one hurts. It’s really hard to face this reality about an old friend,” she wrote on 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,” she said.

Jake Thomas, who also starred in the show, wrote on Instagram: “My heart hurts today. I was fortunate to know Bobby for most of my life. And he was one of the coolest guys you could ever meet.”

Robert Carradine’s daughter, Ever, confirmed the death on her Instagram account and paid tribute to her father. “My sweet, funny dad, who’s only 20 years older than I am, who never missed an opportunity to drive me to the airport or tell me how much he loved my homemade salad dressing, is gone,” she wrote.

Actor Martha Plimpton, Carradine’s niece, wrote on Instagram: “My Uncle Bobby was the best one of all 8 brothers; blood, adopted, and step. Out of all of them, he was the absolute best. He was the one who cuddled me when I came to visit my father in LA for the first time at 8 or 9 years old.”

Born in Hollywood in 1954, Carradine was part of a famous acting family and had more than 150 acting credits to his name. He starred in the successful 1984 comedy movie “Revenge of the Nerds” and had a string of TV appearances.

He was the son of actor John Carradine; brother to Christopher and Keith, and half-brother to David, Bruce and Michael Bowen.

He is also survived by Ian Carradine and Marica Reed Carradine.