Very little is known about the old Russian gods. The chronicles of Vladimir's reign list seven gods whose statues Vladimir had installed in Kiev. The fact that he installed them raises the question: was there no existing temple to the city's gods? Did Vladimir's apparently arbitrary collection of gods reflect a belief system, or a political alliance? (Elsewhere, the chronicle implies that he had no religion of his own.) A few of Vladimir's gods are mentioned again in The Lay of Igor's Men, and virtually nowhere else. It is still unclear whether some of these gods were Russian, or existed at all.
Faced with a seeming paucity of Russian Pagan gods and no mythology to speak of, amateur scholars, out of some kind of obsession with quantity, mixed all known Central European gods into one oversized Pan-slavic pantheon. Some (Glinka, Potebnya) went so far as to invent gods which never existed, or write at length on gods who are known to us only by their names. Unfortunately, even such a highly-respected academician as the archaeologist Boris Rybakov sometimes could not resist the temptation to create myths out of whole cloth (arbitrarily making Veles the god of the underworld, and creating a reptile-god out of the Russian nickname for "Jack"). Fantasy writers Dmitry "Yggeld" Gavrilov and Alexander Asov, and neo-nazi "priests" Vadim Kazakov and Alexander Khinevich, have published whole books cataloging their versions of Slavic gods. Prof. Vladimir Propp, a folklorist, went to the opposite extreme, asserting that Pagan Russia worshipped Nature and did not have any gods at all. In this he is not far from the truth, since Russian folk rites and magical incantations hardly mention any Pagan gods.
Still more confusion was added in recent years with the popularization of The Book of Veles. The book was the creation (or forgery) of the poet Yuri Mirolubov. Mirolubov had previously published Sacralnoye Rusi a confection similar to Gerald Gardner's Witchcraft Today in which he claimed that a Pagan priesthood had survived in northern Russia since the tenth century. In the 1950-s Mirolubov claimed that he had found and translated a set of wooden tablets which told the "aryan" history of Russia. In the prologue he lays out a list of gods in imitation of the Elder Edda. Parts of The Book of Veles have been translated into English, and can be found online. The book, however, has an unpleasant aspect beyond its reputation as a forgery: it has literally become the bible of Russia's neo-nazi Rodnoverie (Native Faith) movement.
American students of Russian Paganism today use Prof. Linda Ivanits's list of Russian gods. Prof. Ivanits has pretty much cleaned the Russian pantheon of duplications and made-up gods. Though she regularly references Rybakov, she generally avoids his arbitrary creations, and her list can be considered reliable.
The list I give below is based on thirty years of my own research in Russian folk beliefs. I have left out some of Vladimir's gods, which do not exist in Russian folk religion, and have included known female deities, who have thus far been all but ignored.
—Russ Gulevitch
Bohg (the word can be pronounced with either an H or a G): The generic word for God. Originally it may have been a short name for Dazhbog, the god of well-being and, most likely, the real chief god of the Russian people.
Máti: The generic word for a Mother Goddess.
Deva: The generic word for a Maiden Goddess.
Mati Zhiva (Mother Life): The life-force who exists without beginning, without end. With her song she created the Gods, the universe, and all living creatures.
Mati Lada (Mother Harmony): She, who maintains peace, and the harmony of Nature and living beings.
Mati Syrá-Zemlyá (Mother Green-Earth — mistranslated as "Mother Moist Earth"): The only Pagan deity regularly mentioned in Russian folklore. Goddess of Nature and the fecund earth. Guardian of oaths; the Russian peasant swore an oath on a piece of turf, and concluded by saying "And may the Earth reject me if I break my word." She replenishes a person's strength when s/he hugs her. When an evil force is banished into the earth, she swallows it beyond all return.
Rozhanitsy (Birthgivers): Collective name of the Mother Goddesses.
Father Svarog: First craftsman, father of the gods and forefather of humans.
Rod (The Clan): Svarog as the forefather of the human race.
Heaven: A more commonly used name for Father Svarog.
Dazhbog (Generous God): Mentioned in the chronicles as one of the seven gods of Vladimir's pantheon, and again, in The Lay of Igor as the forefather of Russian princes. God of the Sun, of rain, of prosperity and well-being. Probably also a god of justice.
Mother Beautiful-Sun: Sun goddess celebrated by the common people.
Perun: Hot-headed god of thunder and battle, from Vladimir's pantheon. Perhaps the god of Rurik's clan (but not Vladimir's since Vladimir was illegitimate!). There is no evidence to support him as the chief Russian god.
Grom Gremuchiy (Rumbling Thunder): Prince Vladimir and his bad-tempered Perun were not very popular with the peace-loving Russians. Russian peasants preferred their own god of thunder, rain, protection and fertility who was more attentive to their needs. With his thunder Grom awakens the Earth in the Spring. He pours rain on the fields when it is needed to make the crops grow, and witholds it in time for the harvest. Whenever Grom sees a malicious spirit, he shoots it with his lightning arrow, which will penetrate anything to hit its prey.
Stribog: One of the seven gods of Vladimir's pantheon, generally considered a wind-god. In The Lay of Igor he guides arrows in battle, which suggests he is a war god — otherwise there is no reason to give a wind god so much prominence.
Velés: Tutelary deity of Novgorod. God of livestock, game animals, magic and prophecy. The Lay of Igor calls the legendary bard Boyan a grandson of Veles, which suggests that Veles is also a god of bardic poetry, and, perhaps, of the other arts as well.
Pätnitsa (Friday): Goddess of women, who should honor her every Friday with a ritual luncheon.
Svarozhich (Son of Svarog): God of useful fire. He has no first name, so that no one may call him by mistake and cause a calamity.
Yarilo or Bright Yar: Springtime god of erotic love and the generative force. He is one of the few Russian gods of whom we have a detailed description, since a peasant youth would portray him in a spring rite. Yarilo is a handsome young man on horseback, barefoot, dressed in white, and wearing a crown of field flowers. In one hand he carries a sheaf of wheat; in the other the head of Old Woman Winter.
Kupála or Kupáva: Bride of Yarilo at the Midsummer celebrations. The name implies swimming (kupatisa), or coupling. Well, at Midsummer they do both!
Marina: Maiden goddess of water. Possibly a sister of Kupava. She appears in the Midsummer celebrations as a red maple sapling decorated with ribbons. After the celebrations she is floated away on the water. Perhaps she is the goddess of maidens who have not married.
Lälia: Twin sister of Leil. Maiden goddess of brides.
Leil: Twin brother of Lälia. Young god of cowherds, folk music, romantic love, and marriage. Best known from Rimsky-Korsakov's opera The Snow Maiden.
Kolädá: Goddess of children and the Winter Solstice celebrations.
Volos (perhaps a variation of Veles): God of livestock and the Winter Solstice celebrations. Appears as a bear. Also known as Ovsen', who appears as a goat.
Nikóla (St. Nicholas): Dazhbog the generous. Gives useful advice to peasants, and protects them against the bad-tempered Elijah. Pictured as a kindly peasant in birchbark sandals, walking the Russian countryside together with the aloof Elijah.
Yegoriy (St. George): Veles.
Ilya (Prophet Elijah): Perun at his most bad-tempered and spiteful. Always defeated by the peasant who follows Nikola's advice.
Iván Kupala (John the Baptist): A male spirit of the Summer Solstice.
Peter Golden-Keys (St. Peter): Grom the rain god. Opens heaven's reservoirs when rain is needed for the crops. Locks them when crops need to dry prior to harvesting. Pictured in the company of Jesus and St. Paul, all three disguised as travelers.
Isús (Jesus): Dazhbog the just, whose job it is to keep an eye on unpredictable deities (especially St. Paul, who is always getting into trouble!).
Bogoróditsa ("Birthgiver of God" — the Virgin Mary): A mother goddess and the most beloved of Russian folk deities.
Paraskeva-Pätnitsa (St. Paraskeva): Goddess of women.