Do I need a Gmail account to log in to Blogger?

We do not require you to have a Gmail address to log in to Blogger or to create a Google Account. If you don't have or want a Gmail account, you can still create a Google Account. A Google Account is made up of any email address and password of your choosing.
However, if you already have a Gmail account, it comes with a built-in Google Account, which you can associate your Blogger account with.