Lithuanian Dievas, Latvian Dievs and Debestēvs ("Sky-Father"), Latgalian Dīvs, Old Prussian Diews, and Yotvingian Deivas was the primordial supreme god in Baltic mythology, and one of the most important deities, together with Perkūnas and the brother of Potrimpo. He was the god of light, the sky, prosperity, wealth, the ruler of gods, and the creator of the universe. Dievas is a direct successor of the Proto-Indo-European supreme sky father god *Dyēus of the root *deiwo-. Its Proto-Baltic form was *Deivas.

Dievas had two sons (Dievo sūneliai (Lithuanian) or Dieva dēli (Latvian)) known as the Heavenly Twins.

Since the conversion of Latvia and Lithuania to Christianity and continuing in modern times, this word refers to the Christian God.^{[unreliable source?][citation needed]}

In English, Dievas may be used as a word to describe the God (or, the supreme god) in the pre-Christian Baltic religion, where Dievas was understood to be the supreme being of the world. In Lithuanian and Latvian, it is also used to describe God as it is understood by major world religions today. Earlier *Deivas simply denoted the shining sunlit dome of the sky, as in other Indo-European mythologies. The celestial aspect is still apparent in phrases such as Saule noiet dievā ("The sun goes down to god"), from Latvian folksongs. In Hinduism, a group of celestial deities are called the devas, a result of shared Proto-Indo-European roots.

The conception of divinity in the old Lithuanian religion is still not always clear to modern scholars. A number of them suggest that Lithuanians had a pantheistic concept to their religion. This concept, according to the ideas of modern researchers, had to include the following:

However, this understanding excludes the conception of a pantheon or of some other possible council of gods in the old pagan Lithuanian religion.

Many well-established sources concerning Lithuanian mythology do not contradict this conception, although there is not much data available. The lack of data leaves a wide gap for interpretations, and as a consequence, many scholars do not agree on all of the points above.

For example, a historian of the early 19th century, Theodor Narbutt, took the presence of the pantheon in Lithuanian mythology as an axiom. And, in spite of being subsequently criticized that his sources were unreliable, and that his interpretations did not always concur with evident data from Lithuanian folklore, Narbutt's mythology was presented in a pictorial and detailed way. His works had a certain influence on the thinking and ideas of some scholars.^{[citation needed]}