Prithvi Raj III, commonly known as Prithviraj Chauhan (1149–1192 CE), was a king of the Hindu Chauhan (Chauhamana) dynasty, who ruled the kingdom of Ajmer and Delhi in northern India during the latter half of the 12th century.

Prithviraj Chauhan belonged to the Rajput Chauhan clan, which according to a legend mentioned in later manuscripts of Prithviraj Raso was part of Agnivanshi Rajputs, derived it's origin from a sacrifical fire-pit. Chauhan was the last independent Hindu king to sit upon the throne of Delhi. He succeeded to the throne in 1169 CE at the age of 20, and ruled from the twin capitals of Ajmer and Delhi which he received from his maternal grandfather Arkpal or Anangpal III of the Tomara dynasty in Delhi. He controlled much of present-day Rajasthan and Haryana, and unified the Rajputs against Muslim invasions. His elopement in 1175 with Samyukta (Sanyogita), the daughter of Jai Chandra Rathod, the Gahadvala king of Kannauj, is a popular romantic tale in India, and is one of the subjects of the Prithviraj Raso, an epic poem composed by Chauhan's court poet and friend, Chand Bardai.

Prithviraj Chauhan defeated the Muslim ruler Shahabuddin Muhammad Ghori in the First Battle of Tarain in 1191. Ghauri attacked for a second time the next year, and Prithviraj was defeated and captured at the Second Battle of Tarain (1192). Sultan Ghauri took Prithviraj to Ghazni, where he was executed. After his defeat Delhi came under the control of Muslim rulers.