Man vs. Man
The most obvious man versus man conflict in Frankenstein is, of course, between the creature and Victor Frankenstein. The creature both loves and hates Frankenstein; he longs for acceptance, but resents the Victor's abandonment of him after his creation. After Victor destroys the creature's intended mate, he swears revenge with the evil promise that he will be with Victor on his wedding night. After the creature murders Elizabeth, Frankenstein vows to stop him at all costs, even to the ends of the earth.
Man vs. Himself
Victor has more than a few of these moments throughout the novel. One such moment that stands out is when Victor agrees, after hearing the creature's pitiful and lonely story, to make him a mate. Victor feels compelled to aid the creature as his Creator, but as he works on making a female, he begins to question the wisdom in making another monster. He worries that it might unleash "a race of devils [...] on the earth" (Ch. 20). Plagued by guilt and recrimination, Victor abruptly destroys his work in progress.
Man vs. Nature
Victor's creation of the monster itself is an act of man versus nature. He defies the laws of nature and reanimates dead tissue. In the moment of creation, Victor reacts with horror at what he has done.
Victor's search through the arctic on his quest to destroy the creature definitely constitutes as man versus nature; the cold, icy conditions and Victor's growing illness challenge his progress.