Marvel Comics © January 1967, Thor #136.  The story is "To  Become An Immortal!", Jane fails Odin's test for immortality and is sent back to Earth with no memory  of Thor or Asgard. Thor encounters the goddess Sif, Heimdall's sister, after many years

Characters:  Thor [Donald Blake]; Jane Foster; Heimdall; Odin; The Unknown (introduction); Dr.Keith Kincaid (introduction); Sif (introduction)

Works by:  Script: Stan Lee    Pencils:Jack Kirby    Inks: Vince  Colletta