Uhlan (/ˈuːlɑːn, ˈjuːlən/; French: uhlan; German: Ulan; Lithuanian: ulonas; Polish: ułan) is a type of light cavalry, primarily armed with a lance. The uhlans started as Lithuanian irregular cavalry, that were later also adopted by other countries during the 18th century, including Poland, France, Russia, Prussia, Saxony, and Austria. The term "lancer" was often used interchangeably with "uhlan"; the lancer regiments later formed for the British Army were directly inspired by the uhlans of other armies (even though they were never known by that name).

Uhlans traditionally wore a double-breasted short-tailed jacket with a coloured plastron panel at the front, a coloured sash, and a square-topped Polish lancer cap (rogatywka, also called czapka). This cap or cavalry helmet was derived from a traditional Polish cap design, formalised and stylised for military use. Their lances were traditionally topped with a small, swallow-tailed flag (pennon) just below the spearhead.

There are several suggested etymologies for the word uhlan. In the Turkic languages, oğlan means 'young man' or 'boy'. It is probable that this entered Polish via Tatar and was styled as ułan. The Polish spelling was then adopted by German, French, and other European languages.

In the late 14th century, Golden Horde Tatar (sometimes spelled Tartar) families settled in Lithuania and so were required to serve the Grand Duke of Lithuania militarily and later the Polish king. The Poles started incorporating much of their military vocabulary and traditions, along with their strategy and tactics. Lithuanian Tatars served as part of the Royal armies during various battles of the late Middle Ages. Their tasks were to conduct reconnaissance in advance of the heavier cavalry banners (knights). With the end of armoured knights during the 16th century, the Lithuanian Tatars were organized in light (Tatar) banners – armed with a light lance, bow, sabre, and, on occasion, a battle axe or horseman's pick, serving as companions (towarzysz) and retainers (pocztowy) – while equally lightly armed hussars were converted into heavy companies of winged hussars. Tatar companions serving within their own Tatar companies (banners) lasted until the 1770s, when major cavalry reforms were carried out within the Polish–Lithuanian army and were included in the reformed cavalry regiments. The last Polish king, Stanisław August Poniatowski, had an uhlan guard regiment simply known as the Royal Uhlans. It was disbanded in 1794 or 1795.

Uhlans frequently adopted the practice of the original Lithuanian lancers of attaching pennons to lances to look more awe-inspiring.

Uhlan units started emerging in Western European armies during the War of Austrian Succession, starting with an uhlan squadron, known as the Natzmer Uhlanen, formed by Frederick the Great in 1740. The next year, the squadron was expanded to an uhlan regiment, finally being transformed into Natzmer's 4th Hussar Regiment in 1742.

Simultaneously, in 1743, Maurice de Saxe formed a mixed uhlan-dragoon regiment, the Volontaires de Saxe, for Louis XV's French Royal Army. It was composed of six companies, each of eighty dragoons and eighty uhlans, and included Lithuanian, Polish and Tatar soldiers. The regiment was known for its bravery, fighting spirit, and alcoholism.

The first uhlan regiments were created in the early 18th century, during the 1720s, in the Polish–Lithuanian Commonwealth.