David Angel

<blockquote>
This plugin takes the images attached to a post or page and creates a looping slideshow, just like the one above. It’s very simple right now, but I’ve got some other neat ideas for it in the future.
Usage is simple: 
 [photofade] – Displays slideshow of images attached to your post/page by Menu Order. Defaults to 4 seconds. 
 [photofade time=’5000′] – Displays the same slideshow with 5 second intervals, configured via milliseconds. 
 [photofade order=’random′] – Displays the slideshow in random order. Options are ‘sequence'(default), ‘random’ or ‘random_start’ 
 [photofade height=’350′] – Displays the slideshow at 350px tall. Control the height in pixels with this. Can also be set to ‘variable’ to allow for different image heights. Defaults to smallest image height. 
 [photofade styles=’off’] – Turns off default styles and use your own (you can use ‘photofade_custom’ class). Defaults to ‘on’.
If you enjoy this plugin, if it makes your life easier, if it saves you time, if you think it’s gorgeous in it’s simplicity, consider donating. I’d love to improve it more.
Note: Plugin works best if uploaded images are of similar size/dimensions.
</blockquote>

PhotoFade

Create a jQuery powered slideshow of the attached images using the [photofade] tag.

MartyThornley

Makes local copies of all the linked images in a post, adding them as gallery attachments.
<h4>Features</h4>
<h4>Credits</h4>
This plugin is baszed on the work done in the “Add Linked Images to Gallery” plugin by http://www.bbqiguana.com/

Import External Images

Funciona perfecto en WP 4.9

Makes local copies of all the linked images in a post, adding them as gallery attachments.

PhotoFade vs Import External Images