What represent the creature?

The creature (much better word than monster) represents a range of ideas and concerns in the novel. Consider the following:

It may be a symbol of science - the novel repeatedly posits science as an alternative way of understanding the world to that offered by religion - the creature represents this in both its power and its deformities (both physical and moral) -

It may be a symbol of Viktor's and society's mysogyny - it is created without the natural loving process of a sexual relationship - the creature's initial creation keeps Frankenstein from being with Elizabeth, as does the murder on his wedding night - highly symbolic.

It may be a symbol of the parent child relationship: it grows up nameless unloved untutored and a moral lesson to parents about their obligations to their children. Recall Shelley's own tragedies losing mother and growing up most alone.

It may be a symbol of human nature, an argument against original sin: even untutored, the creature is initially good until maltreated by society around him, whereupon its rage took over. Notice however that the creature's rage is only directed at those connected to Frankenstein - or others who have hurt him - it is not a loose cannon!

It may be a symbol of the outcast from society: the weak the poor the dispossessed and a comment on the way that society treats them.