question on icloud and creating users
I have noticed that my Macbook Pro will create its own user. I immediately deleted this user since I didn't create it and thought it was taken care of. Well, I turned on my computer again today and the user was created again, without my consent. My initial reaction is to think that this is a virus but I started using iCloud recently to share photos with my family and thought maybe using iCloud will create a user for some reason. This hasn't happened before in the 4 years I have owned the Macbook Pro. I updated to Mavericks so maybe something finally came through in the update. I really have no idea what is going on. All I am used to seeing when I turn on my computer is the administrator (me) and another user I created. Now there is a third user that has been created all by itself. Has anyone encountered this before? Any help would be appreciated!! Basically, I am stressed out because now I think I have a virus.
MacBook Pro (15-inch Mid 2010), OS X Yosemite (10.10.1)