Mary Bos was a schoolmate from the Montessori school. She was an invited guest at Anne's tenth birthday party, and in the well-known photo of that gathering, she is the very slender girl third from the right. Mary was a gifted artist whose drawings and paintings were much admired by her peers. She is mentioned in passing in Anne's diary, when Anne writes of dreaming about Peter Schiff. She and Peter are looking "at a book of drawings by Mary Bos". Little else is known about Mary, but it is known that she did survive the war. 

September 26th, 1928 in Amsterdam (Age 96)