Madame Defarge is the character archetype known as "the witch." An older woman which meets the 'hag-like' standards of "the witch" archetype, Madame Defarge delights in the suffering of others as she knits her shrouds at the foot of the guillotine.
"Instantly Madame Defarge's knife was in her girdle; the drum was beating in the streets, as if it and a drummer had flown together by magic; and The Vengeance, uttering terrific shrieks, and flinging her arms about her head like all the forty Furies at once, was tearing from house to house, rousing the women." (chapter 28)
Madame Defarge's knitting is a nice complement to her character as well:
"Knitted, in her own stitches and her own symbols, it will always be as plain to her as the sun... It would be easier for the weakest poltroon that lives, to erase himself from existence, than to erase one letter of his name or crimes from the knitted register of Madame Defarge." (chapter 15)
With knitting a traditionally an older woman's hobby which plays into our "witch" archetype, Defarge also uses her craft to secretly record names of the revolution's enemies.
Moreover, the "witch" archetype is often out to trap or destroy the heroine of the story. Madame Defarge would like nothing better than to bring about the ruin of Lucy Manette; DeFarge orchestrates the plot to bring down Charles Darnay.
Monsieur Defarge does not figure into the archetypes as well as the Madame, but in my opinion, she fits it perfectly enough for the both of them!
Monsieur and Madame DeFarge of A Tale of Two Cities figure clearly as archetypal villains; in fact, Madame DeFarge is one of Dickens's most memorable of scoundrels. Her complete focus on retribution for the tragic misfortune of her family is evidenced throughout the narrative with her doomsday weaving of the names of the condemned into her knitting.
There was a character about Madame Defarge, from which one might have predicated that she did not often make mistakes against herself in any of the reckonings over which she presided....
Then she glanced in a casual manner round the wine-shop, took up her knitting with great apparent calmness and repose of spirit, and became absorbed in it.
Her implacable hatred and relentless evil intentions are undeterred by her husband's reasonings that there should be a limit to the deaths on the guillotine in Chapter XII of Book the Third,
Well, well,” reasoned Defarge, “but one must stop somewhere. After all, the question is still where?”
“At extermination,” said madame.
When her husband notes how Dr. Manette, for whom he was once a servant, has suffered and how his daughter Lucie has suffered, Madame DeFarge reacts heartlessly at his suggestion to desist from her terrible vengeance:
“Then tell Wind and Fire where to stop,” returned madame; “but don’t tell me.”
Completely without pity, Madame Defarge does not trust her husband to agree, then, with her feelings that Lucie and her daughter should also be exterminated along with the others connected to the Evremonde family. So, she hurries to where Lucie lives in order to kill Lucie and the child herself. But, in her struggle with Miss Pross, the villainous Mme. Defarge is shot by her own gun.
While all of the good characters in Dickens's novel are self-sacrificing, M. and Mme. Defarge consider their cause, their retribution against the aristocracy. And, although Defarge displays some sympathy for the Manette/Evremonde family, he still acquiesces to the iron will of his wife, who, in her sole intention in life as revenge for the deaths of her family, is a fateful force of villainy.