Did you notice that here in Developer's Blog you can see the Author avatar and Bio right after the post?
Well this is not a plugin it's just a few lines of code.
1. Open you single.php file of your theme.
2. Now place the functions (below) inside the Loop.
Look for the post content and put it after it. Then you will be sure is inside the Loop:
3. Add the functions
Get the Author avatar:
Get the Author posts link:
Get the Author Bio:
(please notice the field description must be filled in the author profile page)
You can style the output with tables, divs and CSS.
Enjoy it 😉