David Yost originally auditioned for a different Power Rangers character before he was cast as Billy Cranston. One of the most iconic characters in the franchise, Billy was the only one of the original five Rangers to remain on Mighty Morphin Power Rangers until the very end. While Billy's story was cut short during Zeo, the original Blue Ranger's importance to the show cannot be overstated. Yost's character even establishes a tradition where, a lot of times, the Blue Ranger is the smartest character on their Power Rangers team.