Voltron, one of the most recognizable giant robot shows, was originally an amalgamation of two other Japanese anime shows: Beast King GoLion and Armored Fleet Dairugger XV.
Beast King GoLion was adapted for the “Lion Force Voltron” arc of Voltron, which was the first arc of the series and often the best remembered. Though changes were made to better suit an American audience, GoLion and Voltron share the same basic plot.
GoLion followed a team of five space pilots as they return to Earth to find it obliterated by a nuclear war. They end up being captured by the Galra Empire and forced to fight for their lived, but escape and wind up on the planet Altea, which has also been conquered by the Galra Empire. The pilots discover the GoLion, which happens to be the only thing capable of taking down the Galra forces.
The reasoning behind GoLion’s separation into five smaller robots was that it had become too proud after destroying many enemies, and eventually tried to fight the goddess of the universe. The goddess instead tried to teach it humility by changing the huge, powerful robot into five smaller lion robots that would then lay in wait for worthy pilots to reform the GoLion altogether. These pilots were Akira, Takashi, Isamu, Tsuyoshi, and Hiroshi, who together pilot the GoLion and protect the ruler of Altea, the Princess Fala.
Though GoLion only ever achieved moderate success in Japan during its initial run, when it was turned into Voltron by World Events Productions, it became wildly popular. Because of this, the Voltron version is often preferred by fans rather than the original GoLion release. While Voltron has seen multiple DVD releases over the years, GoLion can be seen in its original form on Crunchyroll.