Asvin Balloo

This plugin will add a “Back to top” icon automatically to your blog. It features a smooth scrolling effect and customizable options such as the color, position and scroll duration, sprinkled with some cool CSS3 effect.
By <a href="http://htmlblog.net/" rel="nofollow ugc">Asvin Balloo</a>.
Supported features:
<ul>
<li>Smooth scrolling animation</li>
<li>Customizable options via the admin panel</li>
<li>Works on almost all browsers</li>
<li>No need to add any markup to your theme</li>
</ul>

WP To Top

This plugin will add a "back to top/ scroll to top" icon automatically to your blog.

jqrambo

The most comprehensive scroll-to-top plugin in the universe. Provides an intuitive button on each page so that, with one click, your readers will be back to the top of the page. Fully customisable from within the Customizer. You can change almost any setting and even upload your own custom image.

CakePress Scroll to top

The most comprehensive scroll-to-top plugin in the universe. Filled with useful features, every aspect can tweaked or customized from within the Custo …

WP To Top vs CakePress Scroll to top