Frieda was Rod Reiss' eldest daughter and Historia's oldest half-sister.
She was the true queen of humanity from 842 to 845. She is known to appear in Eren and Historia's obtained memories. In his Titan form, Grisha invaded an underground cavern under the Reiss family chapel, where the family had gathered to pray. He battled Frieda and consumed her, thus gaining her powers and memories. He then slaughtered her mother and siblings, and finally destroyed the chapel. When Eren later eats Grisha, Frieda's memories are transferred to him along with Grisha's.