James "Big Jim" Rennie is the owner of used car dealership in Chester's Mill. He is also a council man of Chester Mill. After the dome mysteriously appeared, He slowly took in his hand the leadership of the town. His claim to the town's leadership was strengthen when the Police Chief Duke Perkins died. 

He has a son named after him. Junior is a disturbed individual convinced that the dome is making people, specifically Angie sick. He kidnapped her and kept her in their family's fallout shelter. After learning of Junior's action, he initially did not let Angie leave. But later decided to make a deal with her to protect his son. 

Big Jim is played by actor Dean Norris. Dean played the Iconic role of DEA agent Hank Shrader in the TV hit series Breaking BAd