Varāhamihira (c. 20/21 March 505 – c. 587), also called Varāha or Mihira, was an ancient Indian astrologer-astronomer who lived in or around Ujjain in present-day Madhya Pradesh, India.

Unlike other prominent ancient Indian astronomers, Varāhamihira does not mention his date. However, based on hints in his works, modern scholars date him to the 6th century CE; possibly, he also lived during the last years of the 5th century.

In his Pancha-siddhantika, Varāhamihira refers to the year 427 of the Shaka-kala (also Shakendra-kala or Shaka-bhupa-kala). Identifying this calendar era with the Shaka era places Varāhamihira in the 505 CE. Alternative theories identify this calendar era with other eras, placing him before the 5th century CE. However, these theories are inaccurate, as Varāhamihira must have lived after Aryabhata (born 476 CE), whose work he refers to. The particulars of the date mentioned by Varāhamihira - Shukla pratipada of the Chaitra month of the Shaka year 427 - align accurately with 20-21 March 505 CE. Al-Biruni also places Varāhamihira in 505 CE.

In accordance with the contemporary tradition, 505 CE was most probably the year in which Varāhamihira composed Pancha-Siddhantaka or began planning it. However, some scholars believe that it was the year of Varāhamihira's birth or of another important event in his life. This is because according to Amaraja, the author of a commentary on Brahmagupta's Khanda-khadyaka, Varāhamihira died in 587 CE (Shaka year 509). If Varāhamihira wrote his work in 505 CE even at the young age of 25, he must have been over 105 years old at the time of his death, which seems exceptionally high to these scholars. Consequently, these scholars consider date Varāhamihira's lifespan to 505-587 CE. Other scholars doubt the accuracy of Amaraja's statement, since he lived a thousand years after Varāhamihira.

According to a historically inaccurate tradition, Varāhamihira was associated with the first century BCE legendary emperor Vikramaditya. This tradition is based on Jyotirvid-abharana, a work attributed to Kalidasa, which states that Varāhamihira (along with Kalidasa) was one of the navaratnas ("nine gems") at Vikramaditya's court. However, this text is a literary forgery, and is dated variously from 12th-18th century. Varāhamihira definitely did not live in the same century as some of the purported "Navaratnas", such as the much older Kalidasa.

Much of the undisputed information about the life of Varāhamihira comes from a stanza in his Brhaj-jataka. According to this stanza, he was a resident of Avanti, was a son of Aditya-dasa, and studied at Kapitthaka through the boon of the sun god.

Varāhamihira's father Aditya-dasa likely trained him in jyotisha (Indian astrology and astronomy), as suggested by the Brhaj-jataka stanza and the opening stanza of Pancha-siddhantika.

Varāhamihira's commentator Utpala calls him "Magadha-dvija". According to one interpretation, this means that Varāhamihira was Brahmana (dvija), whose ancestors belonged to the Magadha region.