The Heliodorus pillar is a stone column that was erected around 113 BCE in central India in Besnagar (Vidisha), Madhya Pradesh. The pillar is commonly named after Heliodorus (identified by him as a Garuda-standard), who was an ambassador of the Indo-Greek king Antialcidas from Taxila, and was sent to the Indian ruler Bhagabhadra. A dedication written in Brahmi script was inscribed on the pillar, venerating Vāsudeva (Krishna), the Deva deva the "God of Gods" and the Supreme Deity. The pillar also glorifies the Indian ruler as "Bhagabhadra the savior". The pillar is a stambha which symbolizes joining earth, space and heaven, and is thought to connote the "cosmic axis" and express the cosmic totality of the Deity.

The Heliodorus pillar site is located near the confluence of two rivers, about 60 kilometres (37 mi) northeast from Bhopal, 11 kilometres (6.8 mi) from the Buddhist stupa of Sanchi, and 4 kilometres (2.5 mi) from the Hindu Udayagiri site.

The pillar was discovered by Alexander Cunningham in 1877. Two major archaeological excavations in the 20th-century have revealed the pillar to be a part of an ancient Vāsudeva temple site. Aside from religious scriptures such as the Bhagavad Gita, the epigraphical inscriptions on the Heliodorus pillar and the Hathibada Ghosundi Inscriptions contain some of the earliest known writings of Vāsudeva-Krishna devotion and early Vaishnavism and are considered the first archeological evidence of its existence. The pillar has been called one of the earliest surviving records of a foreign convert into Vaishnavism. An alternative interpretation is that making dedications to foreign gods was only a logical practice for the Greeks, intended to appropriate their local power and cannot be regarded as a "conversion" to Hinduism.

The pillar was first discovered by Alexander Cunningham in 1877 near the ancient city of Besnagar in neighbourhood of Vidisha in central India. Besnagar was founded near the confluence of Betwa River and Halali River (formerly, Bais River and the basis for "Bes"-nagar). The fertile region was historically important because it was on the trade route between the northern Gangetic valley, the Deccan and the South Indian kingdoms of the subcontinent. The Besnagar site is at the northeastern periphery of the confluence, and close to Sanchi and Udayagiri, both ancient and of significance to Buddhism and Hinduism.

When Cunningham first saw it, the pillar was thickly encrusted with ritually applied red paste (vermillion). This encrusted pillar was the object of worship and ritual animal sacrifice. Next to the red-colored pillar was a high soil mound, and on top of the mound a priest had built his home and surrounded it with a compound wall. The locals at the time called the pillar the Khamba Baba or Kham Baba.

Cunningham, an avid British archaeologist credited with many discoveries of ancient sites on the subcontinent, saw no inscription due to the thick crust surrounding the pillar. He nevertheless sensed its historical significance from the shape and the visible features such as the crowning emblem, carved fan, rosettes, the faceted symmetry merging into a round section. He also guessed there may be an inscription below the crust, and reported the pillar as, "the most curious and novel" of all his discoveries. Near the standing Besnagar pillar, Cunningham found the remains of a fan-palm pinnacle, which he thought originally belonged to the pillar. Assuming that this broken part was part of the standing pillar, he sketched a composite version. The fan-palm design is otherwise known to be associated to the worship of Samkarsana-Balarama, another one of the Vrishni heroes.

A short distance away, Cunningham found a second pillar capital on the ground with an emblem in the form of a makara (mythical elephant-crocodile-fish composite). He assumed, based on the shape of the bell, which he considered "of true Ashokan proportions", that this broken part was part of a lost pillar of the Ashokan period. Further, about a kilometer away, Cunningham found a third pillar capital of similar style, with an emblem in the form of a kalpadruma (wishing tree). Cunningham assumed this discovery too was related to the Besnagar pillar in some way. The kalpa tree design is otherwise known to be associated to the goddess Sri Lakshmi.

Later research showed that the fan palm pinnacle could not fit, and the discovery of the inscription on the pillar suggested that a Garuda emblem was crowning the structure.