In Mary Shelley's Frankenstein, society unfairly associates physical deformity with monstrosity, reflecting the theme of appearance vs. reality. The creature looks terrifying: so society assumes he must be a monster.

Consider first Victor Frankenstein: from a well-respected family and loved by Elizabeth Lavenza (his foster sister). His best friend is Henry Clerval—decent and loyal. Victor appears to be good, and ethically grounded. (This is ironic because Victor himself appears to be so respectable.) However, when he goes away to school, he becomes involved with the teachings of Professor M. Waldman who encourages Victor to:

...unfold to the world the deepest mysteries of creation.

In doing so, this ethical young man (against the advice of his other teachers) ponders questions deemed better left to God. He is told that man was never meant to create life: only God should do this.

While Victor may at first be motivated to help mankind, he loses sight of the foolishness in his actions; his egotism drives him to achieve what no man before him has—but he is irresponsible. He brings life to his creature, and Victor's reaction is the first we see that judges the being on outward appearance rather than inward substance. Seeing what he has created, Victor flees, abandoning the creature to the world.

Victor is not the only member of society to behave so. The creature finds comfort and safety in the shed attached to the DeLacey home. Here he learns to read, write, speak...and love others. Old, blind DeLacey has no fear of the creature. When the family sees him, however, they treat him like a monster:

At that instant the cottage door was opened, and Felix, Safie, and Agatha entered. Who can describe their horror and consternation on beholding me? Agatha fainted; and Safie, unable to attend to her friend, rushed out of the cottage. Felix darted forward, and with supernatural force tore me from his father, to whose knees I clung: in a transport of fury, he dashed me to the ground and struck me violently with a stick...my heart sank within me as with bitter sickness...overcome by pain and anguish...

Later, when the creature saves the little girl in the woods from drowning, his appearance frightens her father, and he shoots the creature.

However, the creature himself tells us what lies beneath his hideous exterior. He describes how society responds to the "wretched," and chides Victor:

All men hate the wretched; how, then, must I be hated, who am miserable beyond all living things! Yet you, my creator, detest and spurn me, thy creature...You purpose to kill me. How dare you sport thus with life? 

The monster speaks of the gentleness within his own heart:

If any being felt emotions of benevolence towards me, I should return them an hundred and an hundred fold...I would make peace with the whole kind!...Oh! my creator, make me happy; let me feel gratitude towards you...Let me see that I excite the sympathy of some existing thing...

The creature promises that with someone to love, he will disappear forever:

“I swear,” he cried, “by the sun, and by the blue sky of Heaven, and by the fire of love that burns my heart, that if you grant my prayer, while they exist you shall never behold me again."

Society sees the appearance of horror and assumes, therefore, that what lies within must match what is visible. It is the basis of all forms of prejudice.

However, for even a father's love, the creature would not have been "monstrous."