If you study the history of animation, there are few talents that are as influential as Ralph Bakshi. He transformed animation in the 70s and 80s, introducing complex social and adult themes, challenging the status quo of Disney and Hollywood at large. He was the first filmmaker to bring Lord of the Rings to the big screen and his accomplishments have inspired legions of animators, artists and story-tellers working today.
A great place to check out Ralph's work, from past to present, is his Instagram, which is run by his family.
You can purchase limited editions prints, cells and even his current paintings and drawings at his website.
You can rent a lot of his films on Amazon Prime. Check out Lord of the Rings here. But be prepared... Ralph wanted to make another film so it does leave you hanging a bit.