GRUB 2 themes
Nachi Falls (4k)
Anime santa girl (4k)
Velika Outskirts (4k)
Velika (4k)
Tera Elf Priest (4k)
Seoul at night (4k)
Installation
cd to directory with theme you are interested in and run sudo install.sh
Credits
I used Poly light GRUB theme as starting point. Icons and font are taken from there.