The Czechs (Czech: Češi, pronounced [ˈtʃɛʃɪ]; singular Czech, masculine: Čech [ˈtʃɛx], singular feminine: Češka [ˈtʃɛʃka]), or the Czech people (Český lid), are a West Slavic ethnic group and a nation native to the Czech Republic in Central Europe, who share a common ancestry, culture, history, and the Czech language.

Ethnic Czechs were called Bohemians in English until the early 20th century, referring to the former name of their country, Bohemia, which in turn was adapted from the late Iron Age tribe of Celtic Boii. During the Migration Period, West Slavic tribes settled in the area, "assimilated the remaining Celtic and Germanic populations",^{[citation needed]} and formed a principality in the 9th century, which was initially part of Great Moravia, in form of Duchy of Bohemia and later Kingdom of Bohemia, the predecessors of the modern republic.

The Czech diaspora is found in notable numbers in the United States, Germany, Canada, Slovakia, Austria, the United Kingdom, Argentina, Australia, Switzerland, France, Russia, Italy, Israel, Brazil, and Romania among others.

The Czech ethnic group is part of the West Slavic subgroup of the larger Slavic ethno-linguistical group. The West Slavs have their origin in early Slavic tribes which settled in Central Europe after East Germanic tribes had left this area during the migration period. The West Slavic tribe of Czechs settled in the area of Bohemia during the migration period, and assimilated the remaining Celtic and Germanic populations. In the 9th century the Duchy of Bohemia, under the Přemyslid dynasty, was formed, which had been part of Great Moravia under Svatopluk I. According to mythology, the founding father of the Czech people was Forefather Čech, who according to legend brought the tribe of Czechs into its land.

The Czechs are closely related to the neighbouring Slovaks (with whom they constituted Czechoslovakia 1918–1939, 1945–1992). The Czech–Slovak languages form a dialect continuum rather than being two clearly distinct languages. Czech cultural influence in Slovak culture is noted as having been much higher than the other way around. Czech (Slavic) people have a long history of coexistence with the Germanic people. In the 17th century, German replaced Czech in central and local administration; upper classes in Bohemia and Moravia were Germanized, and espoused a political identity (Landespatriotismus), while Czech ethnic identity survived among the lower and lower-middle classes. The Czech National Revival took place in the 18th and 19th centuries aiming to revive Czech language, culture and national identity. The Czechs were the initiators of Pan-Slavism.

The Czech ethnonym (archaic Čechové) was the name of a Slavic tribe in central Bohemia that subdued the surrounding tribes in the late 9th century and created the Czech/Bohemian state. The origin of the name of the tribe itself is unknown. According to legend, it comes from their leader Čech, who brought them to Bohemia. The exact etymology of Čech is uncertain, with most common derivation relating it to the root čel- (member of the people, kinsman). The Czech ethnonym was adopted by the Moravians in the 19th century.

Czechs, like most Europeans, largely descend from three distinct lineages: Mesolithic hunter-gatherers, descended from a Cro-Magnon population that arrived in Europe about 45,000 years ago, Neolithic farmers who migrated from Anatolia during the Neolithic Revolution 9,000 years ago, and Yamnaya steppe pastoralists who expanded into Europe from the Pontic–Caspian steppe in the context of Indo-European migrations 5000 years ago.

The population of the Czech lands has been influenced by different human migrations that wide-crossed Europe over time. In their Y-DNA haplogroups, which are inherited along the male line, Czechs have shown a mix of Eastern and Western European traits. Studies on 1750 and 257 samples found out frequenices of R1a (34.2-36.94%), R1b (24.78%-28.0%), I2 (11.3%), I1 (8.33%), E (5.1-6.63%), G (5.1%), J2 (3.5%), J1 (0-2%), and N (1.6%). The haplogroup R1a is predominantly represented by its more Western Slavic clade R1a-M458 (>30%) as more Eastern Slavic clade R-M558 is in a small minority (<6%). Based on haplotype similarity, Czechs are most similar to neighboring Slovaks, but although "a sharp genetic border was found between Poland and Germany, the frequency distribution of haplotypes in the Czech Republic and its neighbours resembles far more a smooth cline than a sharp border". A mtDNA study of 179 individuals from Western Bohemia showed that 3% had East Eurasian lineages that perhaps entered the gene pool through admixture with Central Asian nomadic tribes in the early Middle Ages.