On the excellent series The Toys That Made Us, former Mattel marketing VP Paul Cleveland explains why He-Man rides around on a giant green cat. Here's the story from Wikipedia but watching him tell it above is much more entertaining:
— Read the rest…While the decision was made for He-Man to have some sort of vehicle, they no longer had the budget to be able to produce one; the decision was then made to repurpose a tiger from the Big Jim toy line.