In Amazing Spiderman #48, Marvel did something rather interesting. They replaced an aging villan (the Original Vulture) with a newer, updated version. Blackie Drago was the cellmate of the OV, and has been pestering him for the secret of his wings. The Vulture, facing death as a result of a machine shop accident, decides to divulge the hiding place of a pair just outside the prison walls.
At this point Blackie laughs and reveals that he was responsible for the accident which injured the Vulture. He wastes little time in breaking out of prison and once he has the wings he seems to be invulnerable, especially since our friendly neighborhood Spiderman is coming down with a cold.
The story comes to a climax atop a bridge, with a hostage and Spidey facing an enemy who can fly. This time, however, the hostage is a nobody and thus does not die. Eventually the new Vulture manages to defeat Spidey, helped a great deal by the latter's illness.
There are a few examples I can think of where an old villain was replaced by a new one in the GA and SA. For example, Batman's old nemesis Two-Face came back as two different people before Harvey Dent himself resumed the role at the very end of the Golden Age. Still, it was not common as of 1967, when this story first appeared, although of course in modern comics there are many examples of crooks retiring and others (sometimes related, sometimes not) taking over their names.
Another interesting aspect to the story is that it's plainly set in the winter in New York, and the weather plays a key role in the story.
In ASM #49, Kraven reappears. Jealous that the Vulture has gotten attention by defeating Spiderman, he resolves to attack Drago. Meanwhile, Peter is still sick and recuperating in bed. Aunt May stops by and insists on calling Dr Bramwell, the family doctor. While Peter is waiting to see him, and starting to feel much better, he learns that Kraven and the Vulture are tearing up the city. So he joins the battle and this time manages to decoy Kraven into kayoing the Vulture before he removes the former's ray gun that so devastated Peter in ASM #47.