Anti-Croat sentiment or Croatophobia (Croatian: Hrvatofobija) is discrimination or prejudice against Croats as an ethnic group, also consisting of negative feelings towards Croatia as a country.

Some of the earliest tensions between the Croatian and Serbian people were documented in the mid-19th century, during the nation-building process. Serbian Prime Minister Ilija Garašanin's Načertanije (1844), initially a secret document, claimed lands that were inhabited by Bulgarians, Macedonians, Albanians, Montenegrins, Bosniaks, Hungarians, and Croats as a part of Serbia. Garašanin's plan also included methods of spreading Serbian influence in the claimed lands. He proposed ways to influence Croats, who Garašanin regarded as "Serbs of Catholic faith." In 1901, Serbian Orthodox bishop Nikodim Milaš published the influential work Pravoslavna Dalmacija, in which he, among others, claimed that the Croatian historical lands and historical-sacral heritage were Serbian since the Early Middle Ages.

Vuk Karadžić and other early Slavists considered everyone speaking Shtokavian dialects to be ethnic Serbs. Hence, the literary and standard Croatian language and heritage, based on Shtokavian, was to be a part of the Serbian language, and all Shtokavian-speaking Croats were counted as "Catholic Serbs." Chakavian was considered by them to be the only original Croatian language, sometimes also Kajkavian which was theoretically related to the Slovenes, and sometimes none dialect (grouping Chakavian with Shtokavian as the Serbian language), reducing Croats to merely a toponym. Croatia was at the time a kingdom in the Habsburg monarchy, with Dalmatia and Istria being separate Habsburg crown lands.

After Austria-Hungary occupied Bosnia and Herzegovina in 1878 and Serbia gained its independence from the Ottoman Empire, Croatian and Serbian relations deteriorated as both sides had pretensions on Bosnia and Herzegovina. In 1902, there was a reprinted article written by the Serb Nikola Stojanović that was published in the publication of the Serb Independent Party from Zagreb titled Do istrage vaše ili naše (Till the Destruction, Ours or Yours). The article denied the existence of a Croat nation, and forecast the result of the "inevitable" Serbian-Croatian conflict.

That combat has to be led till the destruction, either ours or yours. One side must succumb. That side will be Croatians, due to their minority, geographical position, mingling with Serbs and because the process of evolution means Serbdom is equal to progress.

— Nikola Stojanović, Srbobran, 10 August 1902

During the 19th century, some Italian radical nationalists tried to promote the idea that the Croatian nation has no sound reason to exist: therefore the Slavic population on the east coast of the Adriatic Sea (Croats and Slovenes) should be Italianized, and the territory be included in Italy.

A new state was established in late 1918. The Kingdom underwent a crucial change in 1921 to the dismay of Croatia's largest political party, the Croatian Peasant Party (Hrvatska seljačka stranka). The new constitution abolished historical/political entities, including Croatia and Slavonia, centralizing authority in the capital of Belgrade. Nikola Pašić believed that Yugoslavia should be as centralized as possible, creating a Greater Serbian national concept of concentrated power in the hands of Belgrade in place of distinct regional governments and identities.