Dyaus
Dyauṣ Pitā is a minor "Father Heaven" deity of the Vedic pantheon, who appears in hymns with Prithvi Mata "Mother Earth" in the ancient scriptures of Hinduism. He is significant in comparative philology scholarship of Proto-Indo-European religion as similar vocative and nominative concepts have been discovered in other languages, such as Iuppiter (Latin), Zευς πατήρ (Greek), Tius or Zio (Old German) and Toutiks dipater (South-Picenean), all of which like Dyaus Pita mean "sky father".
In the Rigveda, Dyaus Pita appears only in verses 1.89.4, 1.90.7, 1.164.33, 1.191.6, 4.1.10. and 4.17.4. He is thus a marginal deity in Rigvedic mythology.
The name Dyauṣ Pitā is etymologically parallel to the Greek Zeus Pater, and closely related to Latin Roman Jupiter. Both Dyauṣ and Zeus reflect a Proto-Indo-European *Dyeus. This, and many other parallels such as the Indic rain god Parjanyas similarity to Slavic Perun and Norse Thor, Fjörgyn led 19th century scholars to comparative mythology studies and a conjecture that Vedic, post-Vedic, Greek and Roman rituals likely had more ancient Proto-Indo-European roots.
The noun dyaús (when used without the pitā "father") means "sky, heaven" and occurs frequently in the Rigveda, as a mythological entity, but not as a male deity: the sky in Vedic mythology was imagined as rising in three tiers, avama , madhyama, and uttama or tṛtīya (RV 5.60.6).