Just link back to the original if you use it, but mostly have fun! This is to help people realize possible design flaws if your characters are too similar. I highly recommend challenging yourself with this one! Choose characters that you think are very similar to better help you understand where you might need help. See if your viewers can guess your character within the first half! Don't rely on eyes, and hair to differentiate your characters!! Make every subtle nuance unique! This applies for all styles! You can't tell me "But I draw humans, or anime." Look at any GOOD anime character designs and you'll see that you can fill this out for them too! Some good examples to use this meme on for preexisting characters: Cruela Devil, Jafar, Facilier, Cowboy Bebop cast, any of Hanna Barbera's characters or any pre 90s toon, Batman villains, etc.
If you post a link to your meme, I may not respond. I hope you don't find that rude, I just can't check them all I'm afraid, but feel free to post it for others' reference n.n
Here's my example: [link]
And here's an excellent human example by *Altalamatox
If you liked this visual format, you might also be interested in the longform written version here [link]
Another character uniqueness meme! [link]
A 4-character version of this file [link]See my Reference folder for tutorials on how YOU can add variety into your characters!
Here's a few for starts: [link] [link] [link]