Bryan Cranston 'In Deep Despair' Over TV Son RJ Mitte's Death

Bryan Cranston is mourning the devastating loss of his TV son RJ Mitte ... saying he's in "deep despair" following the "Breaking Bad" star's death.

Bryan posted a photo of him and RJ together and wrote in an emotional tribute "I'm in deep despair as I write this tonight. RJ Mitte, my sweet son on Breaking Bad has died."

The actor recalled meeting RJ when he was just 14, praising the young actor for his determination while living with cerebral palsy and his growth from a teenager on the show's set into a talented actor and disability rights advocate.

"He was one of the stars of a hit TV show -- but still a kid," Bryan added.

The actor revealed they had been texting just weeks ago to arrange lunch, expressing heartbreak over their plans never coming to fruition, saying "I do know that I loved him ... I'll miss you, son."

As TMZ first reported, RJ -- best known for playing Walter White Jr. on the hit AMC series -- died at age 34. Sources told TMZ he died by suicide, and authorities are still investigating his death.

Beyond acting, RJ was a passionate advocate for performers with disabilities, using his platform to promote greater representation and inclusion.

Podcast host Joe Vulpis, who saw RJ just weeks before his death, told us RJ was "so positive" and "one of the most kind and genuine people [he] got to speak with." 

Cranston concluded his tribute by urging anyone struggling with suicidal thoughts to seek help through the 988 Suicide & Crisis Lifeline.