Sardinians or Sards are an ethnic group indigenous to Sardinia, an island in the western Mediterranean which is administratively an autonomous region of Italy.

Not much can be gathered from the classical literature about the origins of the Sardinian people. The ethnonym "S(a)rd" may belong to the Pre-Indo-European (or Indo-European) linguistic substratum, and whilst they might have derived from the Iberians, the accounts of the old authors differ greatly in this respect. The oldest written attestation of the ethnonym is on the Nora stone, where the word Šrdn (Shardan) bears witness to its original existence by the time the Phoenician merchants first arrived on Sardinian shores. According to Timaeus, one of Plato's dialogues, Sardinia and its people as well, the "Sardonioi" or "Sardianoi" (Σαρδονιοί or Σαρδιανοί), might have been named after "Sardò" (Σαρδώ), a legendary Lydian woman from Sardis (Σάρδεις), in the region of western Anatolia (now Turkey). Some other authors, like Pausanias and Sallust, reported instead that the Sardinians traced their descent back to a mythical ancestor, a Libyan son of Hercules or Makeris (related either to the Berber verb Imɣur "to grow", to the specific Kabyle word Maqqur "He is the greatest", or also associated with the figure of Melqart) revered as a deity going by Sardus Pater Babai ("Sardinian Father" or "Father of the Sardinians"), who gave the island its name. It has also been claimed that the ancient Nuragic Sards were associated with the Sherden (šrdn in Egyptian), one of the Sea Peoples. The ethnonym was then romanised, with regard for the singular masculine and feminine form, as sardus and sarda.

Sardinia was first settled by modern humans from continental Europe during the Upper Paleolithic and the Mesolithic; at the time Sardinia and Corsica formed a single island, the largest in the Mediterranean, separated from the Italian peninsula by a short stretch of sea. During the Neolithic, Early European Farmers settled in Sardinia. According to modern archaeogenetic investigations, the Neolithic Sardinians showed a greater affinity with the Cardial populations of Iberia and Southern France, furthermore mitochondrial haplogroups of the ancient Mesolithic inhabitants would survive in today's Sardinians.

In the Late Chalcolithic to the Early Bronze Age, the Bell Beaker culture from Southern France, Northeastern Spain, and then Central Europe entered the island, bringing new metallurgical techniques and ceramic styles and probably Indo-European languages. An early modest gene flow of the Western Steppe Herders has been dated to about this period (~2600 BCE).

The Nuragic civilization arose in the Middle Bronze Age, during the Late Bonnanaro culture, which showed connections with the previous Beaker culture and the Polada culture of northern Italy. Although the Sardinians were considered to have acquired a sense of national identity, at that time, the grand tribal identities of the Nuragic Sardinians were said to be three (roughly from the South to the North): the Iolei/Ilienses, inhabiting the area from the southernmost plains to the mountainous zone of eastern Sardinia (later part of what would be called by the Romans Barbaria); the Balares, living in the North-West corner; and finally the Corsi stationed in today's Gallura and the island to which they gave the name, Corsica. Nuragic Sardinians have been connected by some scholars to the Sherden, a tribe of the so-called Sea Peoples, whose presence is registered several times in ancient Egyptian records.

The language or languages spoken in Sardinia during the Bronze Age is unknown since there are no written records of such period. According to Eduardo Blasco Ferrer, the Paleo-Sardinian language was akin to Proto-Basque and the ancient Iberian. In contrast, others believe it was related to Etruscan. Other scholars theorize that there were various linguistic areas (two or more) in Nuraghic Sardinia, possibly Pre-Indo-European and Indo-European.

In the 8th century BCE, Phoenicia founded colonies and ports along the southern and western coast, such as Karalis, Bithia, Sulki and Tharros; starting from the same areas, where the relations between the indigenous Sardinians and the descendants of Phoenician settlers, the Punic people, had been so far peaceful, the Carthaginians proceeded to annex the southern and western part of Sardinia in the late 6th century BC. Well into the 1st century BCE, native Sardinians were said to have preserved many cultural affinities with the Punic people of North Africa.

After the First Punic War, the whole island was conquered by the Romans in the 3rd century BC. Sardinia and Corsica were then made into a single province; however, it took the Romans more than another 150 years to manage to subdue the more belligerent Nuragic tribes of the interior, and after 184 years since the Sardinians fell under Roman sway, Cicero noted how there was still not on the island a single community which had had friendly intercourse with the Roman people. Even from the former Sardo-Carthaginian settlements, with which the Sardinian mountaineers had formed an alliance in a common struggle against the Romans, indigenous attempts emerged aimed at resisting cultural and political assimilation: inscriptions in Bithia dating to the period of Marcus Aurelius were found, and they still followed the old Punic script at a time when even in North Africa the script was neo-Punic; Punic-style magistrates called sufetes wielded local control in Nora and Tharros through the end of the first century B.C., although two sufetes existed in Bithia as late as the mid-second century CE. Overall, Sardinia was quite disliked by the Romans and, as isolated as it was kept, Romanization proceeded at a relatively slow pace.