Board Thread:Naruto Discussions/@comment-28374870-20160504013153/@comment-26773508-20160504080941

In random order:

1) Every Hokage that has ever lived

2) 3rd and 4th Raikage

3) Onoki

4) Nagato, Obito, Itachi, Kakuzu, Kisame

5) Jiraiya and Orochimaru

6) Madara, Izuna, Shisui, Fugaku

7) Gai

8) Kabuchimaru

9) Danzo

10) Hanzo

11) Nartard and Sasgay

I'm not sure about Mei or Konan though. When it comes to power, Mei definitely trumps Kakashi. But I don't know if she'll be able to defeat Kakashi's smarts and versatility. Same with Konan, although judging from the Kakashi vs Konan thread, most agree that Konan beats Kakashi.

And of course, the list is not complete. There are many more who would beat Kakashi. Kimimaro is another one I forgot to mention.