Ken Weatherwax died of a heart attack last weekend aged 59.
His half-brother Joey D Viera confirmed the news.
Weatherwax was best known for his role in Sixties television series The Addams Family, in which he played the son of Gomez and Morticia Addams, Pugsley. The show ran on US channel ABC from 1964 to 1966. The series was later made into two films, first in 1991 and a sequel in 1993.
Born in Los Angeles, he started his career on toothpaste commercials. In addition to his acting work, Weatherwax also served in the US army and worked for Universal Studios as a grip and set builder.
He retired a few years ago due to medical reasons. He is survived by his half-brother as well as a niece and nephew.