- Isobel McGonagall née Ross — wife of Robert McGonagall Sr. and mother of Minerva, Malcolm, and Robert Jr.
- Mr. Ross — father of Isobel
- Mrs. Ross — mother of Isobel
The surname Ross has several possible derivations. The first is as a habitational name taken from Rots, a town in Normandy, France, which was likely named based on the Germanic element rod, meaning "clearing." The second is as a habitational name based on places called Ross or Roose, from the Welsh rhós, "upland" or "moors." The third is from the Germanic personal name Rozzo, a pet form of names beginning with the element hrod, "renown." The fourth is as an occupational name for a person who bred or cared for horses, from Middle High German ros, "horse."