List of Billboard Hot 100 number ones of 1966

The Billboard Hot 100 is a chart published since August 1958 by Billboard magazine which ranks the best-performing singles in the United States.^[1] In 1966, it was compiled based on a combination of sales and airplay data sourced from surveys of retail outlets and playlists submitted by radio stations, respectively,^[1] and 27 different singles spent time at number one.

In the issue of Billboard dated January 1, Simon & Garfunkel reached number one with "The Sound of Silence", displacing the final chart-topper of 1965, "Over and Over" by the Dave Clark Five.^[2] It was the first number one for the duo,^[3] who had broken up following the commercial failure in 1964 of their debut album Wednesday Morning, 3 A.M., on which the track appeared.^[4] In 1965, however, reacting to the growing popularity of folk rock music, Tom Wilson, who had produced the album, created a new mix of the song featuring additional musicians to give more of a folk rock feel.^[4] After it topped the Hot 100, the duo reunited and were extremely successful before breaking up again in 1970.^[4] During February and March 1966, three more acts reached number one for the first time: Lou Christie, Nancy Sinatra, and SSgt. Barry Sadler.^[5] Sadler was a serving member of the United States Army; his song "The Ballad of the Green Berets" honored the military, unusual in an era when many musicians were writing protest songs which opposed United States involvement in the Vietnam War.^[6] It spent five weeks atop the chart, the year's longest run at number one, but was one of only two Hot 100 entries which Sadler achieved.^[7]

Later in the year, the Young Rascals, the Mamas & the Papas, Percy Sledge, Tommy James and the Shondells, the Troggs, the Lovin' Spoonful, Donovan, the Association, ? and the Mysterians, Johnny Rivers, and the New Vaudeville Band all gained their first number ones.^[8] Frank Sinatra topped the Hot 100 for the first time in July with "Strangers in the Night"; the veteran crooner, who was experiencing a career resurgence at the age of 50,^[9] had previously achieved number ones on the separate sales and airplay charts which Billboard published before the launch of the consolidated listing in 1958.^[10] In November, the Monkees gained their first number one with "Last Train to Clarksville".^[11] It was the debut single for the band, which had been put together for the NBC TV comedy series The Monkees, which began airing in September 1966.^[12] The group achieved its second number one with "I'm a Believer" in December, joining the Beatles and the Supremes as the only acts to have two chart-toppers in 1966. Several of the year's number ones have been ranked among the greatest pop songs of all time. In 2004, Rolling Stone magazine placed "Good Vibrations" by the Beach Boys at number 6 in its list of the 500 Greatest Songs of All Time,^[13] and both "Paint It Black" by the Rolling Stones and "The Sound of Silence" also appeared in the top 200.^[14]