Kimba the Lion

The controversy of the century erupted when it was discovered that Kimba the Lion, a 1960s Japanese anime, looked exactly like The Lion King. (Source)

Singing Simba

Four separate actors were used to record Simba's voice: Matthew Broderick, Jonathan Taylor Thomas, Jason Weaver, and Joseph Williams. Broderick and Thomas did the speaking voices, and Weaver and Williams the singing voices. (Source)

The Morning Report

Tim Rice and Elton John wrote a song that ended up getting animated and then cut from The Lion King. It's called "The Morning Report." (Source)