The Stratioti or Stradioti were mercenary units from the Balkans recruited mainly by states of Southern Europe and Central Europe from the 15th century until the middle of the 18th century. They were largely of Albanian origin (about 80%), others were of Greek (most of whom were captains) and South Slavic origin. They pioneered light cavalry tactics in European armies in the early modern era.

One hypothesis proposes that the term is the Italian rendering of Greek στρατιώτες, stratiotes or στρατιώται, stratiotai (soldiers), which denoted cavalrymen who owned pronoia fiefs in the late Byzantine period. It was also used in Ancient Greek as a general term for a soldier being part of an army. According to another hypothesis, it derives from the Italian word strada ("street") which produced stradioti "wanderers" or "wayfarers", figuratively interpreted as errant cavalrymen. Italian variants are stradioti, stradiotti, stratioti, strathiotto, strathioti. In Albanian they are called stratiotë (definite: stratiotët) in French estradiots, in Serbo-Croatian: stratioti, stradioti, in Spanish estradiotes.

Since many stradioti wore a particular cap, in Venice the name cappelletti (sing. cappelletto) was initially used as a synonym for stradiotti or albanesi. In the 16th and 17th centuries the term cappelletti was mainly used for light cavalry recruited from Dalmatia. A feature that distinguished the cappelletti form the stradiotti was their increasing usage of firearms. From the 17th century Venice recruited light cavalry no longer from the Morea, but mainly from Dalmatia and Albania, and the cappelletti gradually replaced the stradiotti. However they had not the same success as light cavalry was gradually abandoned.

The stradioti were recruited in Albania, Greece, Dalmatia, Serbia and Cyprus. Those units continued the military traditions of Byzantine and Balkan cavalry warfare. As such, they had previously served Byzantine and Albanian rulers, they then entered Venetian military service during the Ottoman-Venetian wars in the 15th century. It has been suggested that a ready pool of Albanian stradioti was the product of the northern Albanian tribal system of feud (Gjakmarrja) and consequent emigration. The precise year when stratioti units began to be recruited in western armies is not known. However, under 1371 state decrees of the Venetian Republic those Greeks that lived in Venetian controlled territories were allowed to join the Venetian army.

The precise definition of their ethnic identity was the subject of careful study, while modern scholarship concludes that they were Albanians and Greeks who mainly originated from the Peloponnese. Studies on the origin of their names indicate that around 80% of the stradioti were of Albanian origin, and very few of Slav origin (Crovati). The remainder were Greek, most of whom were captains. Some of the officers' surnames who were of Greek origin are Palaiologos, Spandounios, Laskaris, Rhalles, Komnenos, Psendakis, Maniatis, Spyliotis, Alexopoulos, Psaris, Zacharopoulos, Klirakopoulos, and Kondomitis. A number of them, such as the Palaiologoi and Komnenoi, were members of Byzantine noble families. Others seemed to be of South Slavic origin, such as Soimiris, Vlastimiris, and Voicha. Some renowned Albanian stratioti were the Alambresi, Basta, Bua, Meksi, Capuzzimadi, Crescia, and Renesi. The study on the names of the stradioti does not indicate that most of them came directly from Albania proper, rather from the Venetian holdings in southern and central Greece. The stradioti who moved with their families to Italy in the late 15th and early 16th centuries had been born in the Peloponnese, where their ancestors immigrated in the late 14th and early 15th century, after the request of the Byzantine Despots of the Morea, Theodore I and Theodore II Palaiologos, who invited the Albanians to serve as military colonists in the Peloponnese in the attempt to resist Ottoman expansion in the Balkans.

While the bulk of stratioti were of Albanian origin from Greece, by the middle of the 16th century there is evidence that many of them had been Hellenized and in some occasions even Italianized. Hellenization was possibly underway prior to service abroad, since stradioti of Albanian origin had settled in Greek lands for two generations before their emigration to Italy. Moreover, since many served under Greek commanders and together with the Greek stradioti, this process continued. Another factor in this assimilative process was the stradioti's and their families' active involvement and affiliation with the Greek Orthodox or Uniate Church communities in the places they lived in Italy. On the other hand the military service in Italy and other European countries slowed and in some cases reversed the process of Hellenization. Those Albanians of Greece who migrated to Italy have been able to maintain their identity more easily than the Arvanites who remained in Greece, hence constituting a part of the Arbëreshë people of Italy.

With the end of the Byzantine Empire in 1453 and the breakup of the Despotate of the Morea through civil war between 1450 and 1460, Albanian and Greek stradioti increasingly found refuge and employment with the Venetians. The Republic of Venice first used stratioti in their campaigns against the Ottoman Empire and, from c. 1475, as frontier troops in Friuli. Starting from that period, they began to almost entirely replace the Venetian light cavalry in the army. Apart from the Albanian stradioti, Greek and Italian ones were also deployed in the League of Venice at the Battle of Fornovo (1495). The mercenaries were recruited from the Balkans, mainly Christians but also some Muslims. In 1511, a group of stratioti petitioned for the construction of the Greek community of Venice's Eastern Orthodox church in Venice, the San Giorgio dei Greci, and the Scuola dei Greci (Confraternity of the Greeks), in a neighborhood where a Greek community still resides. Impressed by the unorthodox tactics of the stratioti, other European powers quickly began to hire mercenaries from the same region.

Since the first Ottoman–Venetian war (1463–1479) and later Ottoman–Venetian wars of the 15th and 16th century Stratioti units, both Albanian and Greeks served the Venetian forces in the Morea. In addition the Venetian authorities allowed the settlement of Albanians in Napoli di Romagna (Nauplion) in the Argolis region, outside of the walls of the city. Relations between the two groups and relations between Albanians, Greeks and the central Venetian administration varied. Some families intermarried with each other, while other times disputes erupted as in 1525 when both Greeks and Albanians asked to serve only under the leadership of their own commanders. In the reports of the Venetian commander of Nauplion, Bartolomeo Minio (1479–1483) stressed that the Albanian stratioti were unreliable contrary to the Greek units which he considered loyal. In other reports, attitudes towards Albanians are positive. As Venice lost territory to the Ottomans in the Morea, the numbers of Stratioti the administration employed lowered. By 1524, no more than 400-500 Stratioti remained in Venetian Argolis.