Who is Bertha Mason Rochester from Jane Eyre?

Bertha Mason Rochester is Rochester's first wife. Rochester fell madly in love with Bertha and brought her to Thornfield Hall. During their marriage, this beautiful and tempestuous woman went completely mad. Thereafter, she was carefully kept out of sight in the most upper story of Thornfield Hall. At the end of the novel, we learn that Bertha has burnt down the manor and taken her own life.