Fabian

Easy to use widget to insert customizable social media icons into one of your widget areas. The icons are defined by user, multiple widgets for different user accounts with different stylings are possible.
Customize colors, border-radius and size.

Social Profile Icons Widget

Displays highly customizable social media icons based on user profiles in a widget area.

Patryk Kachel

To use this plugin – your theme (or child theme) must support it. 
To display additional profiles for user you just need to use native WordPress function <code>the_author_meta( 'profile-name' )</code> where ‘profile name’ can be ‘twitter’, ‘facebook’, ‘googleplus’, ‘instagram’, ‘pinterest’.
Code example (with Font Awesome Icons):
<pre><code><?php
 $prefix_twitter_url = get_the_author_meta( 'twitter' );
 $prefix_facebook_url = get_the_author_meta( 'facebook' );
 $prefix_googleplus_url = get_the_author_meta( 'googleplus' );
 $prefix_instagram_url = get_the_author_meta( 'instagram' );
 $prefix_pinterest_url = get_the_author_meta( 'pinterest' );
?>
<?php if ( ! empty( $prefix_twitter_url ) ) : ?><a href="<?php the_author_meta( 'twitter' ) ?>"></a><?php endif; ?>
<?php if ( ! empty( $prefix_facebook_url ) ) : ?><a href="<?php the_author_meta( 'facebook' ) ?>"></a><?php endif; ?>
<?php if ( ! empty( $prefix_googleplus_url ) ) : ?><a href="<?php the_author_meta( 'googleplus' ) ?>"></a><?php endif; ?>
<?php if ( ! empty( $prefix_instagram_url ) ) : ?><a href="<?php the_author_meta( 'instagram' ) ?>"></a><?php endif; ?>
<?php if ( ! empty( $prefix_pinterest_url ) ) : ?><a href="<?php the_author_meta( 'pinterest' ) ?>"></a><?php endif; ?>
</code></pre>
You can see it in action here: https://pencil1.blogonyourown.com/author/robertsummer/

User Social Profiles

Plugin adds social fields to user profile in admin panel (Dashboard > Users).

Social Profile Icons Widget vs User Social Profiles