Hey!
After seeing that gamedesign bundle thread I thought it would be a good idea to have an updated thread with free tutorials and resources for game art and level design.
I'll start with some youtube channels I follow and can keep this up to date as we go like the job census thread.
3D Art (Environment Art/Prop Modelling/Characters etc)
Level Design
level-design.org - Knowledge Base
Interlopers.net
Guiding The Player's Eye
Level Design Inspiration Machine (Tumblr gallery)
Composition in Level Design (Gamasutra version)
2D Art/Concept Painting
Cubebrush (also has some zbrush tutorials)
MrJack (Concept artist on Starcraft II/Heroes of the Storm)
Tyler Edlin (learned a shit ton on this channel)
Иван Смирнов (in russian but some good gems in there)
Game Development
https://game-development.zeef.com/ (large list of softwares and tutorials)
pixelprospector.com (Big List of Game Design Articles)
TigSource Tutorials Forum (also has a lot of game art tutorials)
Others
Parka Blogs (art book reviews)
(Please post your links in the same format so I can just copy and paste them)