Indra, a heroic god, slayer of Vrtra and destroyer of the Vala, liberator of the cows and the rivers; Agni the sacrificial fire and messenger of the gods; and Soma the ritual drink dedicated to Indra are the most prominent deities.
There are two major groups of gods, the Devas and the Asuras. Unlike in later Vedic texts and in Hinduism, the Asuras are not yet demonized, Mitra and Varuna being their most prominent members. Aditi is the mother both of Agni and of the Adityas or Asuras, led by Mitra and Varuna, with Aryaman, Bhaga, Ansa and Daksha.
Surya is the personification of the Sun, but Savitr, Vivasvant, the Ashvins and the Rbhus, semi-divine craftsmen, also have aspects of solar deities. Other natural phenomena deified include Vayu, (the wind), Dyaus and Prithivi (Heaven and Earth), Dyaus continuing Dyeus, the chief god of the Proto-Indo-European religion, and Ushas (the dawn), the most prominent goddess of the Rigveda, and Apas (the waters).
The names of Indra, Mitra, Varuna and the Nasatyas are also attested in a Mitanni treaty, suggesting that the some of the religion of the Mitannis was very close to that of the Rigveda.
Deities by prominence 
List of Rigvedic deities by number of dedicated hymns, after Griffith (1888). Some dedications are to paired deities, such as Indra-Agni, Mitra-Varuna, Soma-Rudra, here counted doubly.
- Indra 289
- Agni 218
- Soma 123 (most of them in the Soma Mandala)
- Vishvadevas 70
- the Asvins 56
- Varuna 46 
- the Maruts 38
- Mitra 28
- Ushas 21
- Vayu (Wind) 12
- Savitr 11
- the Rbhus 11
- Pushan 10
- the Apris 9
- Brhaspati 8
- Surya (Sun) 8
- Dyaus and Prithivi (Heaven and Earth) 6, plus 5.84 dedicated to Earth alone
- Apas (Waters) 6
- Adityas 6
- Vishnu 6
- Brahmanaspati 6
- Rudra 5
- Dadhikras 4
- the Sarasvati River / Sarasvati 3
- Parjanya (Rain) 3
- Vāc (Speech) 2 (mentioned 130 times, deified e.g. in 10.125)
- Vastospati 2
- Vishvakarman 2
- Manyu 2
- Kapinjala (the Heathcock, a form of Indra) 2
Minor deities (one single or no dedicated hymn)
- Manas (Thought), prominent concept, deified in 10.58
- Dakshina (Reward for priests and poets), prominent concept, deified in 10.107
- Jnanam (Knowledge), prominent concept, deified in 10.71
- Purusha ("Cosmic Man" of the Purusha sukta 10.90)
- Apam Napat
See also 
- Noel Seth,"Man's Relation to God in the Varuna Hymns," in the St. Thomas Christian Encyclopaedia of India, Ed. George Menachery, Vol.III, 2010, pp.4 ff.
- Ralph T.H. Griffith, Hymns of the Rigveda (1888).