Olive Hornby was a Hogwarts student in the early 1940s. She teased Myrtle about her glasses, but regretted it later when Myrtle was killed and came back to haunt her (CS16).
Brother, identified only as Mr. Hornby. Brother of Olive. Myrtle haunted his wedding back in the 1940s (GF25).
The first name, Olive, could refer to the "olive branch," a symbol of peace from the early 13th century. "Olive" is from Old French ("olive"), Latin ("oliva"), and Greek ("elaia")