August 6 – In a post-fight interview, Howard Cosell honors Muhammad Ali's wishes to no longer be referred to as Cassius Clay, contrasting with the approach of most other sports reporters of the time.
Summer – Patrick McGoohan quits the popular spy series Danger Man (aired in the US as Secret Agent) after filming only two episodes of the fourth season, in order to produce and star in The Prisoner, which begins filming in September.
September 8 – The first episode of Star Trek ("The Man Trap") is aired.
September 10 – A night of firsts for the Miss America Pageant—its first color TV broadcast and its first airing on NBC.
October 15 – A TV version of the musical Brigadoon is telecast on ABC as a special, using an updated script and story line and re-introducing some of the songs cut from the 1954 movie. The production stars Robert Goulet, Peter Falk and Sally Ann Howes, also featuring Edward Villella and Marlyn Mason. The special airs only one other time, in 1967, before disappearing completely.
October 17 – All of NBC's news programming begins airing in full-color.
December 24 – WPIX in New York City premieres the Yule Log Christmas special which ran every year from 1966 to 1989, but returned in 2001.
Also in 1966
The 1951–53 CBS sitcomAmos & Andy is pulled from syndication broadcast due to complaints from civil rights organizations.
Macdonald Carey starts reciting the epigram "Like sands through the hourglass, so are the days of our lives" at the beginning of his soap opera, Days of Our Lives, a tradition that continues today, over a decade after his death.