Svarog is a Slavic god who may be associated with fire and blacksmithing and who was once interpreted as a sky god on the basis of an etymology rejected by modern scholarship. He is mentioned in only one source, the Primary Chronicle, which is problematic in interpretation. He is presented there as the Slavic equivalent of the Greek god Hephaestus. The meaning of his name is associated with fire. He is the father of Dazhbog and Svarozhits.

The theonym Svarog presents in several forms. The Primary Chronicle has Соварога (Sovaroga), Сварогъ (Svarogǔ), Сварогом (Svarogom), and Сварога (Svaroga). The Sofia Chronograph has Сваро^г (Svaro^g) and Сваро^ж (Svaro^ž).

The fire etymology was one of the first to be proposed by the Slovene linguist Franc Miklošič (1875), who explained the theonym Svarog as consisting of the stem svar ('heat', 'light') and the suffix -og. The stem svar itself was derived from an earlier *sur "shining".

That etymology is also supported by contemporary linguists and etymologists, but the etymology of the stem svar can also be explained differently. The root svar derives from the Proto-Slavic *sъvarъ, which consists of the prefix *sъ- meaning "good, (ones') own" and the stem *varъ "fire, heat", which is continued, for example, by Old Church Slavonic варъ, varǔ ("heat"), or Old East Slavic варъ, varǔ "sunny heatwave, scorching heat, heat" (from Proto-Indo-European *wār- "warmth"). This root was then extended by the suffix *-ogъ, which has no specific function. The common noun *sъvarogъ "good, own fire, heat" was then transferred to the name of the god because of his function as a divine blacksmith, a god wielding fire, working with fire.

The *sъvarъ stem is also the origin of words related to blacksmithing. Some examples are Old East Slavic сварити, svariti "to forge something at high temperature", Old Polish zwarzyć "to weld, chain two pieces of iron", and modern Russian and Slovenian words (e.g. сварить, svarit', variti, "to melt", "to weld").

Some researchers, including Aleksander Brückner and Vatroslav Jagić, have suggested that the name stemmed from the word svar meaning "argument, disagreement", or the verb svariti "to quarrel". Brückner translated this theonym literally as "wrangler, brawler", which would also be associated with fire. However, this etymology has been criticized.

In earlier scholarship, the dominant view was that the root svar was borrowed from an Indo-Iranian language (e.g., from Sanskrit स्वर्, svar "radiance", "sky", "sun"), but this etymology is nowadays rejected due to phonetic difficulties.

After Christianization, Svarog was preserved in toponymy and vocabulary. In Bulgaria these are the towns of Сва́рог, Svarog, Сва́рошка бара, Svaroshka bara, in the Czech Republic it is the Svaroh mountain, and the Sorbian name Zwarogk. Brückner also added the Polish town of Swarożyn here, based on a notation in the German Latin Swarozino from 1205, but the original notation was Swarozina and is dated 1305, so it should be read as Swarocino, from the personal name Swarota, or, as other records indicate, the town was called Swaryszewo, from the personal name Swarysz. Modern notation Swarożyn should be regarded as false transcription.