Folders in local disk

[Hcb]

 I just noticed my local disk (Y) is almost filled. Random labeled folders are filling it up. Can a virus or hacker place labeled folders in there? Or do folders have to have been placed in there by a person? The folders are filled with files consisting of videos and pics that I did not place there. Could someone else in my house have placed them there?

[SuperDave]

You really should check with anyone who has access to this computer and find out what they are doing with the computer.