installing themes (can't find the parent)

Each time I download a theme...unzip...then look in the theme folder..all I see is the child theme.
Hence every time I upload to my site I have a broken theme.
I don't see other people with this problem so I presume I am doing something wrong.
Isn't the parent theme supposed to be in the theme folder with the child theme?
I must be missing something,...plugins I can install...I am using filezilla...but the problem appears before I do the install and after I unzip.
I can't see where the parent theme is.