A longtime Hollywood character actor is dead after a shocking stabbing ... and cops say the man accused of killing him is his girlfriend's son.

According to LAPD, 81-year-old actor James Handy -- whose credits include "Top Gun: Maverick," "Jumanji" and "Arachnophobia" -- was found Wednesday morning in front of a Tarzana home with a stab wound to the chest. He was rushed to a hospital, where he was pronounced dead.

Police say the suspect -- 44-year-old Michael Gledhill -- made a bizarre 911 call before officers arrived ... allegedly telling dispatchers, "I am the son of man, I just killed the man of sin."

When police arrived at the scene, officers say Gledhill flagged them down and admitted he was the person they were looking for. Authorities say he lived at the home with his mother, who was Handy's girlfriend.

Gledhill was arrested and booked for murder, with his bail set at $2M. Investigators have not publicly discussed a possible motive.

Handy was a familiar face to generations of moviegoers and TV fans ... racking up more than 100 acting credits over a career spanning five decades, making the circumstances surrounding his death all the more tragic.

RIP