The Dollars Trilogy (also referred to as the Man with No Name Trilogy) is a series of Spaghetti Western films directed by Sergio Leone, consisting of A Fistful of Dollars, For a Few Dollars More, and The Good, the Bad and the Ugly.
The films were not originally intended to be a series, but the American distributor, United Artists, invented the concept for marketing purposes, establishing Clint Eastwood's character in each film to actually be the same person. Thus, the films have been considered by many to be a series ever since.
A series of novels released in the years after the films establish the films as belonging to the same continuity.
Although the films were not originally envisioned as a series, they do not contain any major continuity errors when viewed as such. When considered a series, the chronological order of the films is also unclear. However, it can be deduced that the films take place in the following order: The Good, the Bad and the Ugly, For a Few Dollars More, A Fistful of Dollars.
The Good, the Bad and the Ugly would take place first, as grave markers are seen marked 1864 and the Civil War (which is still active during the film's events) ended in 1865, thus placing the film in either of these years. Additionally, the "Man with No Name" is seen acquiring his attire in this film that he wears in the previous two films.
For a Few Dollars More takes place after The Good, the Bad and the Ugly because Colonel Douglas Mortimer is a veteran of the Civil War, which – by the time of the film's events – is over. Furthermore, a newspaper archive is seen in the film containing the year 1873.
The only factor that sets For a Few Dollars More before A Fistful of Dollars is that the "Man with No Name's" hat is shot several times, creating holes in it that are visible in the latter film.