NCIS star Pauley Perrette - who plays lab technician Abby Sciuto in the hit US drama - was attacked outside her Hollywood home on Thursday night.
The actress, who was hit in the face several times, told Twitter followers she thought she was going to die. In a lengthy post, she described the man as "psychotic", adding, "I am shaken and traumatised... I almost died tonight".
Police said a man was later arrested for aggravated battery. Los Angeles police officer Jane Kim confirmed the actress's account of the assault was accurate.
She said 45-year-old David Merck was charged with aggravated battery. Bail has been set at $100,000 (£66,000). In her account of the assault, 46-year-old Perrette described Merck as a "a VERY psychotic homeless man".
"He grabbed me so forcefully, pinned my arm, punched me in the nose, forehead, repeatedly telling me he was going to kill me."
Perrette said her attacker "headed towards Hollywood Blvd, with murder in his eyes".
She recalled how, as she lay collapsed on the ground, a man walked past "on his phone, annoyed. Did nothing."