The Little Hedgehog in the Fog of 1975. This 10-minute film based on Sergei Kozlov's script, in 2003 was voted "No. 1 animated film of all time." I always loved this deceivingly simple but profoundly philosophic and highly poetic work, where answers are intended to be found, not just given away.
Sergei died at 70, without to taking too seriously his huge talent.
Yet, talent has taken him for good.