"Last Train to Clarksville" is the debut and number-one single by The Monkees, included on the group's 1966 self-titled album, that was released one month later.

Recorded at RCA Records Studio A, Hollywood, on July 25, 1966, "Last Train to Clarksville" peaked at number one on the Billboard Hot 100 chart in the United States.

According to the song's authors, Tommy Boyce and Bobby Hart, the song is their protest of the Vietnam War and tells the story of a young man who has been drafted. He is waiting for the train that will take him to an army base, and he knows he may die in Vietnam. At the end of the song he states, "I don't know if I'm ever coming home." Like many hit Monkees songs of the era ("Cuddly Toy," "Pleasant Valley Sunday"), the song pairs a fast, chipper melody with darker lyrics. Micky Dolenz performs the lead vocals, with Boyce playing acoustic guitar.

The song has been compared to The Beatles' "Paperback Writer", both in the style of "jangly" guitar and the chord structure. It also resembles the guitar riff in "Blue's Theme", by Davie Allan and the Arrows, from the Peter Fonda biker movie The Wild Angels. The opening/recurring guitar riff on the song "Find Your Way Back", written by Craig Chaquico and performed by Jefferson Starship on their 1980 album Modern Times, is almost identical to the one on "Last Train" in note structure, but very dissimilar in tempo and meter.

Though the Clarksville in the song's title appears to refer to the city of Clarksville, Tennessee—and by implication to nearby Fort Campbell, Kentucky, which is home to the 101st Airborne Division—Hart who did not create the theme for the song states that this is a coincidence and that the choice of the name "Clarksville" was settled on for the way it sounded, after similar names like Clarkdale had been rejected. There are a few other "Clarksvilles" in the U.S., near military training centers, where the song could be set, which helped to make the song a favorite for many people during the Vietnam War. Phillip E. Meyers, who conceived the theme for the song, said that it is specifically intended to imply Fort Campbell and any military center near the other Clarksvilles. The song is not intended to be a protest, but a sensitive focus upon the sacrifices that the US soldiers and their families were making to serve in Vietnam. The reason they were taking the last train was because they wanted to spend all of their last hours with their families before possibly dying in Vietnam. The song was used in an Army produced film shown to new inductees, as early as November, 1967, and at least in the big induction center at Ft. Jackson, South Carolina. It played as the film showed new recruits getting off the train at Ft. Jackson, and would get a big laugh from the men watching the film.

Ed Bruce covered the song in 1967.

The Plastics covered this song (in their electropop style) on their debut album Welcome Plastics.

Cassandra Wilson recorded a jazz cover of the song on her 1995 album New Moon Daughter.

On January 15, 2008, a cover of the song was made available as downloadable content for the music video game series Rock Band. The January 2009 issue of PlayStation: The Official Magazinelists The Monkees' "Last Train to Clarksville" as fourth on its list of Rock Band’s "Five Most Unexpectedly Rockin' Downloadable Songs."

The Standells did a cover version in 1966 on their album The Hot Ones.

George Benson has done an instrumental version in his jazzy style.

It was also covered by the Four Tops on their album Reach Out.

Riblja Čorba released a cover titled "Zadnji voz za Čačak" (trans. "Last Train to Čačak") on their 1987 album Ujed za dušu.

The Cory Daniel Band play a country-rock version of the song at most of their concerts.

R.E.M. performed this song live in their early years.