Lika (Croatian pronunciation: [lǐːka]) is a traditional region of Croatia proper, roughly bound by the Velebit mountain from the southwest and the Plješevica mountain from the northeast. On the north-west end Lika is bounded by Ogulin-Plaški basin, and on the south-east by the Malovan pass. Today most of the territory of Lika (Brinje, Donji Lapac, Gospić, Lovinac, Otočac, Perušić, Plitvička Jezera, Udbina and Vrhovine) is part of Lika-Senj County. Josipdol, Plaški and Saborsko are part of Karlovac County and Gračac is part of Zadar County, and it takes up about 12% of Croatia's land area.

Major towns include Gospić, Otočac, and Gračac, most of which are located in the karst poljes of the rivers of Lika, Gacka and others. The Plitvice Lakes National Park and Northern Velebit National Park are also in Lika.

Since the first millennium BC the region was inhabited by the Iapodes, an ancient people related to Illyrians. During the Gallic invasion of the Balkans, a division of the Gallic army passed through the territory of today's Lika and a part of this army settled among the Iapodes.

In the 2nd century BC, Iapodes came into conflict with the Roman Empire, suffering several military campaigns, most significantly in 129 BC, 119 BC and finally being conquered in 34 BC by Augustus Caesar.

Bijelohrvati (or White Croats) originally migrated from White Croatia to Lika in the first half of the 7th century. After the settlement of Croats (according to migrations theories), Lika became part of the Principality of Littoral Croatia. Lika then became a part of the Kingdom of Croatia in 925, when Duke Tomislav of the Croats received the crown and became King of Croatia.

The name of Lika is derived from old Illyrian language, meaning "body of water"; its cognates are liquor ("fluid") in Latin and liqén ("lake") in modern Albanian. Indeed, a major feature of the Lika landscape are rivers and lakes, as well as marshes and floodplains, many of which have been drained in 18th to 20th centuries. The name initially referred to Lika River, and over time came to denote the region. The first mention of Lika as a toponym appears in 10th-century Constantine Porphyrogenitus' book De Administrando Imperio as βο(ε)άνος, in a chapter dedicated to Croats and the organisation of their state, describing how their ban "has under his rule Krbava, Lika and Gacka".

Among the twelve noble Croat tribes that had a right to choose the Croat king, the Gusić tribe was from Lika. The ethnonym Guduscani mentioned in medieval sources was also thought to be related to Lika.

In 1493 the Croatian army suffered a heavy defeat from the Ottoman forces in the Battle of Krbava Field, near Udbina in Lika. As the Ottomans advanced into Croatia, the Croatian population from the region gradually started to move into safer parts of the country or abroad. Many indigenous Chakavians of Lika leaving this area and to their places mainly arriving Neo-Shtokavian Ikavians from western Hezegovina and western Bosnia, and Orthodox (Vlachs and Serbs Neo-Shtokavian Ijekavians) from south-east of Balkan Peninsula. In 1513 the town of Modruš, the location of the episcopal see in Lika, was overrun by the Ottomans. In 1527 they captured Udbina, including the Udbina Castle, leaving most of Lika under Ottoman control. The region became initially part Sanjak of Bosnia, later the Sanjak of Klis and finally the Sanjak of Krka. The devastation of Lika and Krbava was such that almost half a century they remained largely uninhabited. At the end of the 16th century the Ottomans started settling Vlachs in the area, as well as Muslims in larger settlements where they soon formed a majority of the population.