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Harriet Horne is the owner of the Horne Costume Company, a business that makes Halloween costumes.
Scooby-Doo (DC Comics)
Harriet Horne had no idea that her costumes were being mail-ordered to be used by criminals. They didn't want to disrupt her livelihood, so they didn't tell her about the crime connection. Instead, they asked for a catalog so they could identify her work in the future. The next catalog arrived with a new line of non-monster costumes inspired by Velma, Shaggy, and Scooby. (Costume Caper)