Here's a breakdown:
* Humanity's Influence: The novel explores the conflict between civilization and the primal instincts of nature. Buck, the protagonist, is forced into a life of domestication, but his wild nature constantly pulls him back towards his ancestral roots. This conflict represents the overarching antagonist, making civilization itself a powerful force opposing Buck's natural desires.
* Specific Human Characters: Several human characters embody the antagonist force.
* The Man in the Red Sweater: This character represents the cruel and brutal side of humanity. He represents the abuse and mistreatment Buck endures during his early days of being forced into a life of slavery.
* Hal, Charles, and Mercedes: This trio embodies human incompetence and ignorance. Their lack of understanding and care for Buck's needs ultimately lead to his escape and return to the wild.
* The Harsh Environment: The Alaskan wilderness, while ultimately freeing for Buck, also presents challenges and dangers. The harsh environment is a constant struggle for survival, becoming an antagonist in its own right.
Ultimately, the antagonist in *The Call of the Wild* is a complex web of societal pressures, human cruelty, and the unforgiving nature of the wild. It's not a single bad guy, but rather a collection of forces that drive the story and shape Buck's journey.