Junior Rennie is the son of Big Jim Rennie. In the TV show he is obsessed with Angie Mcalister. He went as far as kidnapping her and keeping her in their fallout shelter since he believes that the dome is making her sick. As the story progresses, He was deputized by the new Police Chief Linda Esquivel.

Junior seems to be showing some signs of mental illness. In reality, he has a brain tumor masking as migraines. Junior also doesn't have a good relationship with Barbie. In the beginning of the series, Junior pick a fight with Barbie because he saw Angie and Barbie outside the hospital.

Junior is played by Alexander Koch