For example, Ilse Langner from AoT. She only appears in the OVA but i simply adore her.
Another example is Matt from Death Note, he appeared in the anime for like two minutes lol. But i still love him.
Weird, but it's true XD

Draco isn't in Monster Musume much but I still love her to death. XD

And not sure if it counts as much, but Angel doesn't have too horribly big of a role in Blue Exorcist (yet), but I love him so much~

I hated that Lust died in FMA!

I know this is a manga, but I absolutly adore Rina Higashikata from Jojo's Bizarre Adventure, even though she only appeared in the total of like 3 pages.

Yes... he who will not be named

^ I have a feeling it's Zeref? I may be wrong bt wtv lol

"Yes... he who will not be named" Voldemort?! (I'm just kidding. Don't mean to make fun).
Rip van Winkle from Hellsing Ultimate is one character I really liked. Shame she only appeared for about one episode.

Lol, i thought about Voldermort too but he has too much screentime to fit in this list, and he's not from an anime lol xD
Your Natsu icon is beautiful btw *^*

Heh, I know. Oh, thanks!

Ramen guy (best girl) from Naruto rofl

^ Ramen guy is Bae ~

Matt - Death Note
Rantaro Amami - DanganRonpa V3:Killing Harmony
Marco Bott - Attack On Titan

way too often xD