Metroid Shyvana
(Disclaimer: This is not my work but I think it would be a good basis for a skin if they added dragon gauntlets.)
I would enjoy a metroid themed shyvana skin that fell under the 1350+ quality that let her turn into ridley instead of a dragon. There are already a ton of video game inspired skins within league so I am sure Riot knows the game of how to pay homage to a series without copyright infringement.
I think there could be a neat upgrade system with flame breath and/or burnout turning a different color with each ability point that is put into them.
Update: Well, we did it everyone. We got over 2,000 people to look at this idea and hopefully a few Rioters that have a soft spot for the Metroid series. Thank you for taking the time to read the ramblings of a madman

is a fusion of Jetstream Sam and Raiden for MGS: Rising
Star Guardian
is Sailor Moon
Grungy
is Oscar the Grouch and cookie monster from from Sesame street,
King
is Bowser
Wicked
is Cruella De vil from 101 dalmatians
Chosen
is a Jedi Knight
Yellow Jacket
is Scorpion and Frozen Shen is Sub-Zero from Mortal Kombat.
Greybeard is Gandalf from Lord of the Rings
Warrior Princess
is Xena
Spectacular
is the incredible hulk
Cryocore
is Mr. Freeze
Augmented
is Bane
in General is Batman
in general is Poison Ivy
Steel Legion
is literally a Grey Knight from Warhammer 40k and Steel Legion
, basically a Sith Lord. He even uses the Force in his recall.
Full Metal
is basically yoda for example. I was just trying to get eh point across, I am sure there is way more I forgot.
Mecha
Mecha
Arcade
Phoenix
VS 
Crimson Elite
Battlecast
Galactic
Galactic
Galactic