Shirley Jackson's short story "The Lottery" depicts an annual event in a village in which the villagers gather in order to have the heads of extended families draw slips. The family with the marked slip is the "chosen" family and must thereby draw slips again to determine which family member will be selected.
Tessie Hutchinson ends up drawing the unfortunate marked slip in this event, resulting in her being selected as the target for the grand finale; Tessie is stoned to death while lamenting how unfair the situation is.
If Tessie is the protagonist of the story, we can identify the rest of the town—everyone who participated in the lottery process and her subsequent stoning—as the antagonist. We can also, in a less tangible sense, identify the concept of mob mentality and the strict reigns of ritualistic tradition as the thematic antagonist.
If you are looking at the entire story of “The Lottery” and are using Tessie Hutchinson as the protagonist, than there are two options as to who or what the antagonist of the story is. First, you could say that all of the other characters – the entire village including her family -- are the antagonists because at the end of the story, they are all in opposition of her. The second option is more symbolic; the whole idea of tradition and keeping traditions alive can be considered the antagonist. The town continues a tradition that they do not know how it began and do not even practice every ritual as it was originally supposed to be practiced. But, because of this tradition and the town’s belief that this tradition must continue, Tessie ends up dying in the end; therefore, making her the protagonist and tradition the antagonist.
In "The Lottery" the antagonist may be difficult to identify because it is not a character or person in the story. Typically the antagonist is the adversary of the protagonist, this is most often another character in the story, however, in this story, the protagonist is Tessie and her adversary is the Lottery itself. The "Lottery" represents a tradition and in the story the person who wins the lottery will be put to death because of that tradition. This creates the conflict in the story and creates the adversarial relationship between Tessie and "The Lottery".