Monstrosity can be defined as an outrageous or ugly person or thing; monster.
Frankenstein had this strange thought about creating life, and eventually had the ambition to do it. This process though, turned him into a mad man. He turned away everyone he loved and everyone who loved him. After he successfully created life he realized how dangerous this creature was and he abandoned him. The new life wasn't dangerous, he was confused. Frankenstein was VERY irresponsible for creating his monster, but he was even worse for leaving it alone. After regaining some, if not most of his sanity, he encountered his creation again. He decided to make a deal with the devil and create another monster, this being female. If he did the monster wouldn't hurt his family and friends. Frankenstein made a second monster, but then decided to take it apart. The monster became very angry and threatened to kill Victor on his wedding night. Frankenstein deserved everything that came at him. He decided to risk the lives of others before himself. The monster did what he said...sort of. He decided to kill all of Frankenstein's loved ones. After everyone was dead, Victor wanted revenge. Frankenstein became the real monster.
The Monster
From the evidence provided, I believe the monster would not have been as monstrous is people didn't judge him and if his creator Victor Frankenstein just took the time to help him, raise him, and show him the ways of being a human. He was born like any human being, not knowing anything like a blank sheet of paper waiting to be written on. His creator abandoned him and he was left on his own to figure out what to do. Since society is so judgemental from his appearance, they didn't even give him a chance. The creature was isolated; he had a craving to be loved and have a companion and tried so hard to make friends but it never worked. The creature did horrific things from being angry at his creator for leaving him. That still doesn't give the creature an excuse for why he killed so many people. Murder is murder, it's wrong. The monster couldn't understand his life and how to deal with it because he was never taught. The monster in the end realizes what he has done.