In the original trilogy, Luke gets his father's blue lightsaber, and the prequels would have been hard-pressed to explain that away. In the end, Darth Vader's red lightsaber had to come along ...

Darth Vader didn't always have a red lightsaber. Early concept art by Ralph McQuarrie (pictured below) shows Vader wielding a blueish-white blade, the same as the Jedi. After all, Vader was always ...