How many people has Jim killed in Under the Dome? This is a serious question, as I'm starting to wonder if Jim is a greater threat to humanity than the dome and what's inside it.
From Wikia of the character Jim, he has killed 18 people directly and one indirectly. You can see it in the character detail in the side section.
Killed Victims: 18 killed
1 indirectly killed
You can also see the list of killed victims there.
Lester Coggins (pushed his head to the Dome; hearing aid exploded)
Boomer Platt (killed in an explosion of a propane tank)
Agatha Seagrave (caused; drowned)
Maxine Seagrave (shot once)
Otto Aguilar (shot once)
Dorothy "Dodee" Weaver (fatally shot in the chest)
Lyle Chumley (fatally stabbed in the chest)
Philip "Phil" Bushey (indirectly; jumped off a cliff after Big Jim closed the path to Zenith)
Rebecca Pine (bludgeoned to death)
Andrea Grinnell (fatally shot in the head)
Marston (throat slashed)
Carolyn Hill (unknowingly; crushed by falling debris)
Hektor Martin (shot in the head)
Kyle Lee (bludgeoned to death with a trophy)
James "Junior" Rennie (stabbed in the heart in self-defense)
3 unnamed Chester's Mill residents (1 man stabbed in the back and 2 men sliced in their necks)
2 unnamed farmers (both shot while fighting for the well on Ollie's side)