The cast of “Breaking Bad” is paying tribute to their late co-star RJ Mitte following his death at age 34 on Monday.

The actor and disability rights advocate was known for his portrayal of Walter “Flynn” White Jr., the son of Bryan Cranston and Anna Gunn’s characters in the Emmy-winning drama.

Mitte died by suicide, his rep confirmed to multiple media outlets.

Cranston, in a post to social media on Monday, wrote that he was in “deep despair” over the death of his “sweet son” on the show.

“I met him when he was only 14 years old when he was cast as Walter White Jr., a part he played with such joy and enthusiasm,” wrote Cranston of Mitte, who — like his character in “Breaking Bad” — had cerebral palsy.

“Born with Cerebral Palsy, he never - ever - allowed that challenge to be an excuse for anything,” he continued. “He met the demanding shooting schedule head on with great determination.”

Cranston wrote that Mitte was “always listening to the advice that his TV parents” gave him before adding, “but being a teenager, sometimes mischievously ignoring the counsel in order to learn the hard way… He was one of the stars of a hit TV show - but still a kid.”

“That kid was pretty raw when we started shooting the pilot in February of 2007, but little by little we watched him grow into a really fine actor.”

Cranston went on to emphasize how Mitte used his experience on the hit show to be a disability rights advocate.

“All that promise and potential now is such a loss. It is especially devastating to hear that he took his own life. Why? We were texting each other just a few weeks ago - figuring out when we could meet for lunch. I don’t know if that lunch would have changed his future…,” he wrote.

“But I do know that I loved him, and thoroughly enjoyed being with him throughout the years on the series, and after the spotlight on Breaking Bad dimmed… I’ll miss you, son.”

The actor also included information for the 988 Suicide & Crisis Lifeline.

Aaron Paul, who played Jesse Pinkman in the show, wrote in a statement to The Hollywood Reporter that he was “at a loss” and “heartbroken” over the news of Mitte’s death.

“RJ, I love you my friend. You will be missed,” Paul wrote.

“And to whoever happens to be reading this, please know you are loved, and you are not alone. Always remember that.”

Dean Norris — who played Mitte’s onscreen uncle in the show, Hank Schrader — reacted to the news on X, writing, “Oh my God! Was working just found out about RJ I am heartbroken. Though RJ didn’t play my TV son, I always looked out for him as a young kid on set.”

“He was a sweetheart of a young man and will be greatly missed. This is so heartbreaking, I can’t believe it. Thinking of him and his family. 💔💔💔💔💔💔.”

If you or someone you know needs help, call or text 988 or chat 988lifeline.org for mental health support. Additionally, you can find local mental health and crisis resources at dontcallthepolice.com. Outside of the U.S., please visit the International Association for Suicide Prevention.

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