In Mary Shelley's Frankenstein tension is great. Within this tension exists an oxymoron.
Victor Frankenstein creates the Monster. After he is able to bring the Monster to life, Victor wishes to end the life of the Monster.
An loosely defined oxymoron exists here given Victor struggled to give life to his Monster, but immediately after looking in to eye of the creature Victor wishes to extinguish the life he so painstakingly created.
The tension created from this 'oxymoron' exists given the fact that Victor places himself in a very precarious predicament: create another life or face certain pain. Therefore, the creation of his monster, which lead to his problem (wishing to destroy the monster) forces Victor to consider recreating life again- something he wishes he had never done in the first place.