Vidar is one of the young generations of the gods who survived Ragnarok, the cataclysmic end of space in Norwegian mythology. (In some stories about this event, that is, in others, the universe simply ends and no one survives.) Almost all references to it in Old Norwegian literature concern its role in Ragnarok; we know little about its personality or function outside this particular episode.
During Ragnarok, the gods - the divine forces that maintain cosmic order - and the giants - the divine forces of chaos and destruction - fought and most of those involved on both sides were killed. God Odin was eaten by the wolf Fenrir. Vidar, Odin's son from the giant Greens, immediately set the wolf to avenge his father's death. He wore a shoe that was made for this particular moment. It was the strongest and strongest shoe of all, and of course, loaded with magical properties. With his help Widar hit the lower jaw of the wolf, and then, keeping the beast's upper jaw open, he cut Fenrir's mouth into pieces with his sword, killing the beast and ending his devastating rage.
Elsewhere, Vidar is called the "silent god", although there is no explanation for this epithet. They say he is the strongest of the gods after the Torah. His land is described as a place of bush and high grass, but the significance of the association of this particular landscape and this god is unknown.
Two toponyms from Norway contain his name: Virsu (from Virarskhof, "Temple of Vidar") and Viskyol (from Virarskjalfa, "Crag/Pinnakl Vidar"). This seems to indicate that Vidar appeared in Norwegian pagan religious practice and that he was not just a literary figure.
Turning to the archaeological record, the depiction of a man tearing the jaws of a wolf on the Cross of Gosforth from northern England and the Cross of Kirk Andreas from Human Island, both dated around 900 AD, could have been Vidar and Fenrir. But they could also have been Christ and a more common wolf, as Christ defeated various monsters was a popular motif in medieval art, and artists often freely mixed pagan and Christian images in the same works Even if they are images of Vidar and Fenrir, they do not give us any new information, but only additional confirmation of the motif, which is often enough repeated in literary sources to leave no doubt about its authenticity.
Unfortunately, then we only know about Vidar as Odin's avenger and Fenrir's killer. Few other tantalizing but misleading details add to any particular, let alone comprehensive portrait of the individual or mythological/religious role. Unfortunately, the question of who exactly was Vidar for the pre-Christian North and other Germanic peoples is, in fact, beyond answer.