The Destroyer (Thor)
Cursed by the death goddess Hela to never die, Thor was left a puddle of mashed flesh by the Midgard Serpent. But when Loki sent the Destroyer to harass puddle Thor, Thor was able to seize control of the mystical armor. Using the Destroyer's awesome power, Thor stormed through Hel and forced Hela to lift her curse, restoring him to full life and vitality.
The story is the finale of Walt Simonson's brilliant run on Thor. If you haven't read it, it's well worth your time to do so.