Allegedly turned down a recurring role on "Falcon Crest" (1981) in the 1970s in order to focus on his business interests.
As of 2010, is the last surviving cast member of "The Green Hornet" (1966).
During the run of "The Green Hornet" (1966), Williams pushed to give more screen time for co-star Bruce Lee, both to help his friend and martial-arts instructor and to help the show survive by playing up the most popular cast member of the show. The producers refused since they didn't want to take attention away from the star, especially to a nonwhite actor.
He and his long-time wife Vicki have three children. They met in Hawaii where she was a surfing pro. He also has twin daughters from a prior marriage.
His neighbor in Ketchum, Idaho, is "Batman" (1966) star Adam West. The two are good friends. In 1967, Williams and Bruce Lee guest-starred opposite West in the "Batman's Satisfaction" episode of Batman.
Spent several months a year in Southern California as a reserve deputy with the Malibu station of the Los Angeles County Sheriff's Department.