Hermóðr is the god who traveled to Hel to try to bring Baldr back to life.
After Baldr was killed through Loki’s scheme, the Æsir were overwhelmed with grief. Hermóðr agreed to ride to Hel and ask its ruler to release Baldr. He used Odin’s eight-legged horse, Sleipnir, and traveled for nine nights through dark valleys before reaching the Gjöll bridge and Hel’s gates.
Hermóðr found Baldr seated in a place of honor and pleaded with Hel. She agreed that Baldr could return only if all things, living and dead, wept for him. Nearly everything did—but the disguised Loki refused, so Baldr remained in Hel. This means Hermóðr’s journey was a rescue attempt, not a successful resurrection.
The Prose Edda calls Hermóðr Odin’s son and Baldr’s brother, although manuscript wording varies. He is sometimes confused with Odin, who sent him, or with Baldr, whom he sought to save.