There is a name on the plaque, just under Stephen Proudfoot. A girl's name, Elizabeth, followed just a space later by a majestic capital R. Elizabeth R. The rest of the girl's last name, for there was obviously more at some point, has been rubbed away by the passage of time.
The second letter is slightly visible, just enough so that people can guess that it could have been a j or a l or an i. New students at Hogwarts make a little game of it, trying to guess that girl's last name. To them, she is just a name on a plaque that commemorates a war fought more than seventy years ago. The game is a friendly little initiation game amongst the houses. What first year can come up with the most ridiculous last name?
The students don't know Elizabeth R. They don't know that she was the youngest child in a family of four children. That she lost every member of her family during the War, except her elder sister. The students don't know that Elizabeth R and her sister joined the Battle of Hogwarts late because they had been on the run for six months. They don't know that the only reason Elizabeth R and her sister knew about the Battle was because of the D.A coin Elizabeth had grabbed before they escaped their home.
The students don't know, can't know, what happened to Elizabeth R that night. They don't know that she fought and defeated men twice her age in battle. They don't know that Elizabeth saw Fernier Greyback lunging at her sister and blasted him away from her. They don't know that Greyback then turned his attention to her, overpowered her and ripped her throat out with his teeth before throwing her body out of a window in the Astronomy Tower.
The students of Hogwarts don't know Elizabeth R. So they play.