R2-D2

Star Wars: Before Empire Strikes Back came out. R2D2 was Luke's father. Luke's father was mortally wounded by Vader. His brain was removed from his body and placed in life support inside a robot. This is why C3P0 is so worried about R2's operational status. C3 knows that R2 has biological components. Turns out Luke, who got very little Jedi training, isn't all that great. It's his Jedi father, inside of R2, every time. Early on, when Luke does something with the force R2 is always there, except for the one time on Hoth and what is R2 doing at that time? Deploying a long-range force antenna we never see again.