Co-Authors Plus
Assign multiple bylines to posts, pages, and custom post types with a search-as-you-type input box.
Tag Plugin: co-authors
Author Box, Guest Author and Co-Authors for Your Posts – Molongui
Easily add an author, a guest author or multiple authors to your posts and display…
Genesis Co-Authors Plus
Enables full support for the Co-Authors Plus plugin in Genesis.
Wpi Multiple Contributors
This plugin facilitates in assigning and displaying more than one author on a post.