WordPress.org

1. Download Plugin, unzip it and upload it to the to the root of your Wordpress "plugins" folder (should be file wp-content/plugins).
2. Acivate it on the admin panel.
3. You get the list of authors wherever you want (sidebar or separate page) by using the function wpallauthors.

This function includes:

optioncount=1 The number of posts of each author is shown. If you don't want this, write 0 instead of 1.

hide_empty=0 Users without posts are shown. If you only want to show users with posts, use an 1 instead of 0:

exclude_admin=0 The administrator of the blog is shown. If you don't want this, use the 1 instead of 0.

You can use all parameters of wordpress-function wp-list-authors.

That's it! The plugin is for free use. If you like it, don't give money, but a comment ;-)

Enjoy!