‘Buffy the Vampire Slayer’ Star Nicholas Brendon’s Cause of Death Revealed

Nicholas Brendon’s cause of death has been revealed following the Buffy the Vampire Slayer star’s death at 54 years old.

Nearly two months after Brendon’s family announced that he had “passed in his sleep of natural causes,” the actor was determined to have officially died of atherosclerotic and hypertensive cardiovascular disease, according to an autopsy report obtained by Page Six.

Atherosclerosis is a specific form of arteriosclerosis in which plaque builds up on artery walls and causes arteries to narrow, blocking blood flow, as per the Mayo Clinic.

Acute pneumonia and previous myocardial infarction — commonly known as a heart attack — were both listed as contributing factors. Brendon’s death was determined to be natural, with the mechanism listed as a 90% blockage of his right coronary artery.

The Psycho Beach Party actor had a lengthy history of health problems, including a cauda equina syndrome diagnosis, which occurs when the nerve roots in the lumbar spine are compressed, cutting off sensation and movement, as per the American Association of Neurological Surgeons.

In 2021, Brendon underwent two spinal surgeries, and in 2022, he was rushed to the hospital during a cardiac incident. Brendon’s manager, Theresa Fortier, told the Los Angeles Times that year that he had been diagnosed with a congenital heart defect following a second cardiac incident.

Fortier added at the time that the second spinal surgery Brendon had undergone resulted in leaking cerebrospinal fluid that caused tachycardia at the time of his second cardiac event. In April 2025, Brendon also underwent a C5/C6 spinal fusion surgery.

The actor’s family announced his death on March 20, writing on social media, “We are heartbroken to share the passing of our brother and son, Nicholas Brendon. He passed in his sleep of natural causes.”

Calling Brendon “passionate, sensitive and endlessly driven to create,” the family continued, “Those who truly knew him understood that his art was one of the purest reflections of who he was.”

“While it’s no secret that Nicholas had struggles in the past, he was on medications and treatment to manage his diagnosis and he was optimistic about the future at the time of his passing,” they went on. “Our family asks for privacy during this time as we grieve his loss and celebrate the life of a man who lived with intensity, imagination and heart. Thank you to everyone who has shown love and support.”