Stills from Bakshi's Lord of the Rings.
I was shown this movie when I was pretty young and, for me, it's the defining version of Tolkien's tale. I'm not saying it's better than Jackson's verison, but was so seminal for me that I can't escape it. The red eyes peering out of the gloom against hallucinogenic backgrounds haunts me to this day.
Also, the costumes the Ring Wraiths wear are pretty bonkers. That, combined with the moaning, shambling, leper-like incarnations as black riders makes them the stuff of nightmares.