Born: c. 1505, Died: Feb. 13, 1542
Known for: Being the queen's sister-in-law; gossiping non-stop; encouraging Henry's fifth wife to have an affair. (Source)
There isn't much to say about Lady Jane Rochford, who begins the book as Jane Parker. As George's fiancée, Jane just wants to be pretty and popular and rich. She watches Mary "as if she were trying to discover the trick of being a desirable girl" (2.172).
As Jane gets older, all the Boleyns consider her "a most poisonous woman" (8.29), because she's always gossiping and spreading rumors. In fact, it's Jane who spreads the rumors that eventually lead to Anne's death. Maybe Anne should have taken poison lessons from Jane.