In A Fistful of Dollars, Leone used a distinct visual style with large face close ups to tell the story of a hero entering a town that is ruled by two outlaw gangs, and ordinary social relations are nonexistent. The hero betrays and plays the gangs against each other to make money. He uses his cunning and exceptional weapons skill to assist a family threatened by both gangs. His treachery is exposed, and he is severely beaten, but in the end, he defeats the remaining gang. The interactions in this story range between cunning and irony (the tricks, deceits, unexpected actions and sarcasm of the hero), and pathos (terror and brutality against defenseless people and against the hero after his doublecross has been revealed). Ennio Morricone's innovative score expresses a similar duality between quirky and unusual sounds and instruments, and sacral dramatizing for the big confrontation scenes. Another important novelty was Clint Eastwood's performance as the man with no name—an unshaven, sarcastic, insolent Western antihero with personal goals in mind, and with distinct visuals to boot—the squint, the cigarillo, the poncho, etc.

The spaghetti Western was born, flourished and faded in a highly commercial production environment. The Italian "low" popular film production was usually low-budget and low-profit, and the easiest way to success was imitating a proven success. When the typically low-budget production, A Fistful of Dollars, turned into a remarkable box-office success, the industry eagerly lapped up its innovations. Most subsequent spaghetti Westerns tried to get a ragged, laconic hero with superhuman weapon skill, preferably one who looked like Clint Eastwood: Franco Nero, John Garko, and Terence Hill started out that way; Anthony Steffen and others stayed that way throughout their spaghetti Western careers.

Whoever the hero was, he would join an outlaw gang to further his own secret agenda, as in A Pistol for Ringo, Blood for a Silver Dollar, Vengeance Is a Dish Served Cold, Renegade Riders, and others, while Beyond the Law has a bandit infiltrate society and become a sheriff. There would be a flamboyant Mexican bandit (Gian Maria Volonté from A Fistful of Dollars, otherwise Tomas Milian, or most often Fernando Sancho) and a grumpy old man, often an undertaker, to serve as sidekick for the hero. For the love interest, ranchers' daughters, schoolmarms and barroom maidens were overshadowed by young Latin women desired by dangerous men, for which actresses, such as Nicoletta Machiavelli or Rosalba Neri, carried on Marianne Koch's role of Marisol in the Leone film. The terror of the villains against their defenseless victims became just as ruthless as in A Fistful of Dollars, or more, and their brutalization of the hero when his treachery is disclosed became just as merciless, or more—similar to securing the latter's retribution.

In the beginning, some films mixed some of these new devices with the borrowed U.S. Western devices typical for most of the 1963–1964 spaghetti Westerns. For example, in Sergio Corbucci's Minnesota Clay, that appeared two months after A Fistful of Dollars, an American style "tragic gunfighter" hero who confronts two evil gangs, one Mexican and one Anglo, with (as in A Fistful of Dollars) the leader of the latter being the town sheriff.

In Johnny Oro, a traditional Western sheriff and a mixed-race bounty killer are forced into an uneasy alliance when Mexican bandits and Native Americans assault the town. In A Pistol for Ringo, a traditional sheriff commissions a money-oriented hero played by Giuliano Gemma (as deadly but with more pleasing manners than Eastwood's character) to infiltrate a gang of Mexican bandits whose leader is played typically by Fernando Sancho.