Skrymir is the largest giant that Thor, Loki and Thialfi have ever seen. He is a friendly giant, who serves them as a guide to a magical place called Útgard.

The giant is extraordinary in the sense that he seems to be unscathed when Thor hits him with Mjölnir.

It turns out that Skrymir is but an illusion created by Útgard-Loki. This explains why he was not hurt by the mighty swings of the god of thunder.