Big Jimmy is the father if Little Jimmy, and the husbot of Akiba. He was built in Wisconsin in 1988. Big Jimmy's father left him at a young age to be with a newer, more well-built robot. So, when Big Jimmy and Akiba built Little Jimmy, he vowed to stay with his family. It was the best moment of his life.
Now, Big Jimmy helps out the BrainPOP gang in whatever ways he can. One of his favorite friends is Moby, because he knows he can count on him and get brilliant robot advice.