The honest description of the Slavic pantheon begins with an admission: its shape is a reconstruction, and specialists differ on how much shape the evidence will bear.
What is reasonably secure is a scatter of gods attached to places and peoples. Perun, the thunder god, is the most widely attested and the best candidate for a head of the pantheon, and his name is cognate with thunder gods elsewhere in the Indo-European field. Veles is opposed to him in a way that has been read as a myth of conflict, though the reading is inferred rather than recorded. Svetovit at Arkona, Svarog, Dazhbog, Mokosh and others appear in one region or one source and not in others.
The Kiev list of 980 in the Primary Chronicle, where Vladimir sets up idols before abandoning them, is the closest thing to a stated pantheon in the whole corpus. It names Perun first. It is also a prince's state cult, erected briefly for political reasons and demolished within a decade, and whether it represents Slavic religion generally is exactly what is argued about.
Of the making of the world, nothing survives that can be shown to predate Christianity. The atlas records that as unknown rather than as debated, because there is no argument in progress: the question was set down for want of evidence rather than settled. What would reopen it is named in the Open Questions panel.