El-Clasico, the greatest rivarly of Football Clubs Barcelona and Real Madrid

The two best teams in a national league frequently have a passionate rivalry, and this is especially true in La Liga, where the match between Barcelona and Real Madrid is referred to as "The Classic" (El Clásico). The clubs were viewed as representatives of the two cities as well as of the two competing regions of Spain, Catalonia and Castile, from the beginning of national championships. One commentator has described the competition as a recreation of the Spanish Civil War, reflecting what many see as the political and cultural conflicts between Catalans and Castilians. The head-to-head record between the two clubs over the years is 52 draws, 97 wins for Barcelona, and 100 victories for Real Madrid.

Before an El Clasico in 2012 at the Camp Nou, Barcelona supporters created a mosaic of the Catalan flag.

Barcelona "had established a reputation as a symbol of Catalan identity, in opposition to the centralizing inclinations of Madrid, as early as the 1930s."

When Francisco Franco began the Coup d'état against the democratic Second Spanish Republic in 1936, Josep Sunyol, the president of Barcelona and a member of the Republican Left of Catalonia and The Cortes, was detained and killed by Franco's soldiers without a trial. Sunyol visited Republican soldiers in the region north of Madrid as part of his political efforts.

All regional languages and identities in Spain were discouraged and restricted under the dictatorships of Miguel Primo de Rivera and, in particular, Francisco Franco. As a result, the fascist-like government was fiercely opposed by the majority of Barcelona residents. Barcelona adopted the phrase "More than a club" during this time because of its purported association with Catalan nationalism and progressive ideals.

The degree to which Franco's rule (1939–75) affected Barcelona and Real Madrid's actions and performance on the field is still up for debate. Both clubs' supporters often exaggerate the myths that support their respective storylines. The majority of historians concur that Franco did not have a favorite football team, but because of his support for the establishment clubs like Atlético Aviación and Real Madrid FC (that recovered its royal name after the fall of the Republic).

Instead of a Catalan team, he also wanted the rebranded CF Barcelona to be successful as a "Spanish squad." Real Madrid only won two Copa del Generalsimo championships and one Copa Eva Duarte during the early years of Franco's dictatorship, whereas Barcelona won three league titles, one Copa del Generalsimo, and one Copa Eva Duarte. Atlético Aviación was thought to be the preferable team at the time instead of Real Madrid.

The most contentious events of the time were Real Madrid's 11-1 victory over Barcelona at home in the Copa del Generalisimo, which the Catalan team claimed was due to intimidation, and Alfredo Di Stéfano's contentious transfer to Real Madrid in violation of his contract with Barcelona. The latter move was a component of Santiago Bernabéu, the chairman of Real Madrid, "revolution," which launched an era of unrivaled hegemony. With Real Madrid dominating not just Spanish but also European football, Bernabéu, a Civil War veteran who fought for Franco's forces, helped establish the European Cup, the first real competition for the top club teams in Europe.

When Real Madrid began to win back-to-back league championships and the first five competitions for the European Cup in the 1950s, his ambition was realized. These things affected Franco's mindset and had a big effect on Spanish football. Historiographers claim that at this point he understood the significance of Real Madrid for the reputation of his government on a global scale, and the club went on to become his favorite team up until his passing.

During his tenure as Franco's foreign minister from 1957 to 1969, Fernando Maria Castiella said of Real Madrid, "[It is] the best embassy we have ever had." After Franco's death in 1975, Spain quickly moved toward democracy. Real Madrid won 14 league championships, six Copa del Generalsimo crowns, one Copa Eva Duarte, six European Cups, two Latin Cups, and one Intercontinental Cup during his reign. Barcelona won 8 league championships, 9 Copa del Generalsimo trophies, 3 Copa Eva Duarte titles, 3 Inter-Cities Fairs Cups, and 2 Latin Cups within the same time span.

When the teams disagreed over the acquisition of Alfredo Di Stéfano, the rivalry grew more heated in the 1950s. While playing for Los Millionarios in Bogotá, Colombia, throughout an Argentine players' strike, Di Stéfano had impressed both Barcelona and Real Madrid. The directors of Barcelona traveled to Buenos Aires soon after Millonarios' return to Colombia and reached an agreement with River Plate, the final FIFA-affiliated team to have Di Stéfano's rights, for his transfer in 1954 for the equivalent of 150 million Italian lire (according to other sources 200,000 dollars).

The two Spanish rivals engaged in a conflict over his rights as a result. Former head of the Spanish Football Federation Armando Muoz Calero was chosen by FIFA to serve as a mediator. Di Stéfano was permitted to play in Madrid for the 1953–54 and 1955–56 seasons as well as Barcelona for the 1954–55 and 1956–57 seasons by Calero.

The Football Association and each club's respective organization gave their approval to the arrangement. Although the Catalans were in favor of the decision, the Blaugrana members were not, and the president was compelled to quit in September 1953 as a result. Barcelona gave Madrid their part of the ownership in exchange for Di Stéfano moving to Los Blancos and signing a four-year deal. Real Madrid paid 5.5 million Spanish pesetas for the move, plus a 1.3 million bonus for the acquisition, an annual fee to be paid to the Millonarios, and a 16,000 peseta salary and bonus for Di Stéfano—a sum equal to 40% of the Madrid club's yearly earnings.

Di Stéfano scored twice in Real Madrid's opening match against Barcelona, and he went on to play a crucial role in the team's following success. Madrid won the first five trophies of the European Cup with his help. Real Madrid and Barcelona faced off against each other twice in the European Cup during the 1960s, with Madrid winning both games en route to their fifth straight championship in 1959–60 and Barcelona winning both games en route to losing the final in 1960–61.

Spanish media dubbed the 2002 match between the two teams in Europe the "Match of the Century," and more than 500 million people watched Madrid's victory. At the Santiago Bernabéu Stadium in 2009, Barcelona captain Carles Puyol kissed his Catalan armband in front of furious Madrid fans. In 2017, Lionel Messi celebrated his 93rd-minute winner for Barcelona against Real Madrid at the Bernabéu by taking off his Barcelona shirt. This intense match is distinguished by its indiscipline in addition to memorable goal celebrations from both teams, often involving mocking the opposition.