In the beginning of the novel...
1) Victor's revenge in defying his father
"But the cursory glance my father had taken of my volume by no means assured me that he was acquainted with its contents, and I continued to read with the greatest avidity." (page 25)
Victor continued to read the books of natural philosophy by Cornelius Agrippa, in defiance of his father's wishes.
2) Victor's revenge in pursuing math and science
"...I at once gave up my former occupations, set down natural history and all its progeny as a deformed and abortive creation, and entertained the greatest disdain for a would-be science which could never even step within the threshold of real knowledge." (page 27)
After witnessing the tree destroyed by lightning, Victor begins to study math and science obsessively as a sort of revenge on "wasting" so much time studying natural history.
In the middle of the novel...
1) The monster's revenge on the cottagers
"But again when I reflected that they had spurned and deserted me, anger returned, a rage of anger, and unable to injure anything human, I turned my fury towards inanimate objects." (page 127)
The burning of the De Lacey cottage is the monster's first major act of revenge; the reader begins to see the evil side of the monster developing.
2) The murder of William
"'Frankenstein! You belong then to my enemy - to him towards whom I have sworn eternal revenge; you shall be my first victim.'" (page 131)
This is the monster's first murder; it becomes evident at this point that revenge has become the monster's obsession.
3) The monster's request for a companion
"'My companion must be of the same species and have the same defects. This being you must create.'" (page 133)
This request is the...