Marvel Comics © June 1968, Thor #153.  The story "--But Dr. Blake Can Die!".  Loki has stolen Thor's hammer and fled to Midgard.  Thor and Sif pursue him, but without the hammer Thor changes into Don Blake as Loki attacks them. Loki escapes, but Sif is injured in the fight, and Dr. Blake  must operate to save her life.

Characters: Thor; Sif; Karnilla; Balder; Loki; Don Blake; Ulik; Odin

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