Cognition level 1:
The popular conception is that the monster in Mary Shelley's Frankenstein, or the Modern Prometheus, was named Frankenstein.
Cognition level 2:
People who think they "know something" about Frankenstein recognize that Frankenstein was the name of the university student who created the monster (thanks Evil Catullus for clarification).
Cognition level 3:
A son generally shares the surname of his father. Those who have also read Carlo Collodi's Pinocchio (part of Project Nodeberg) would realize that Pinocchio, like the monster, could be considered the "son" of the creator. For example, just as Geppetto Baccigaluppo's "son" is named Pinocchio Baccigaluppo (until he gets adopted), Victor Frankenstein's "son" (the monster) also has a surname of Frankenstein. The biggest difference is that while Pinocchio initially runs away from Geppetto, Victor abandons his creation (thanks sfc), putting the "son" status in question.
on the other hand:
<StrawberryFrog> Pinocchio did not have a perfectly good human brain before Geppetto carved him.