Katie Luther, First Lady of the Reformation: The Unconventional Life of Katharina von Bora, by Ruth A. Tucker. This sympathetic biography presents the results of research as well as conjecture and opinion when facts are scarce. For a recent review, see:
Luther and Katharina, by Jody Hedlund. An entertaining and imaginative historical romance about this famous couple.
Katharina: Deliverance, by Margaret Shea. The author describes her novel as biographical fiction and works hard to stay close to the known facts and avoid imposing her modern perspective on Katharina’s life. Shea wrote an article, “The Footsteps of Katharina,” about her research and writing of this novel. See: https://historicalnovelsociety.org/the-footsteps-of-katharina-margaret-skea-on-the-wife-of-martin-luther/
Do you have a favorite book about Katharina?