Of all the explanations for a character cheating death, the revival of Cal Rankin was among the most impressive.
With his ability to absorb the powers of super-beings spiraling dangerously out of control, Cal Rankin (Mimic) went into hiding in a secluded area of Canada. Seeking a cure for his predicament, he enlisted the scientific know-how of Henry McCoy (Beast).
Escaping from authorities, Hulk leapt through Canada and crashed into the log cabin where Mimic was staying. In fighting off the green goliath, Beast noticed that Hulk seemed far weaker than usual, as Mimic was draining the strength Hulk originally acquired from exposure to gamma radiation. But instead of turning green and becoming more powerful himself, Mimic grew ill from radiation poisoning. The issue ended with Mimic left for dead (Incredible Hulk #161).
On the trail of the monstrous Wendigo (who first battled Hulk in #162), Wolverine originally appeared in Incredible Hulk #180-181 as a super-powered agent of the Canadian government.
In an amazing twist of fate, Marvel Comics Presents #59 surmised that because Wolverine was already in the general vicinity at the time, Mimic survived by inadvertently duplicating Wolverine's mutant healing factor and physical traits.
The top panel comes from Incredible Hulk #161.
The version of Mimic who appeared in the Exiles had an altogether different fate as a member of the Defenders.