Considering how time-consuming the process of animation is, it's no wonder that the majority of animated films are short. Since Western animated films are often marketed to children, the short runtimes can also prevent kids, and adults, from getting restless and help them stay focused. However, there are some animated movies, including some of the longest Disney movies ever, that tell stories too big to be constrained by a short runtime.
It's no shocker that one of The Lord Of The Rings movies counts as one of Western cinema's longest films. However, it's not the one people think. Before the popular movie trilogy with Elijah Wood and Ian McKellen, there was an animated film that was released in 1978 based upon the J.R.R Tolkien novels.
The total runtime of The Lord of The Rings is 132 minutes. The film actually performed quite well and John Hurt even voiced the character of Aragorn. There was no sequel made, however, and the film actually ends with the siege of Helm's Deep.