Elga Marker

Elga Marker, niece of Elda

Elga Marker (エルダ・マーカー, Eruga Mākā) is a surviving member of the Marker family in Europe revealed in the last chapter of the manga. She is a daughter of Elda's brother, which makes her a first cousin of Henry. Due to the close kinship with Elda and Karin, her outer appearance resembles greatly with the two.
Elga frustrated

Elga frustrated with Frederick disobeying her orders.

She sent Frederick to investigate Sister Rosary after she inherited the legacy of the Vampire hunting church from Sister Alyssa. However, after Frederick refuses to kill the last member of the church, she attempts to take Rosary's life herself only to find her nephew Frederick had decided to protect Rosary. After he reveals he is responsible for Rosary entering the church in the first place, she leaves him to do as he pleases.