Quick, who killed more people — on-screen — in Star Wars' original trilogy: Luke Skywalker or Darth Vader?
Even if you throw out the Death Star (368,891 — and Wookieepedia says that baby only seated 342,953) that's still 849 kills, more than half of that coming when Skywalker blows up Jabba's sail barge in Return of the Jedi. Also, if killing monsters like the Rancor counts, why wasn't the Wampa included? That would make it 369,741.
Compare that to Vader's body count:
• Episode 4: Eight — Poor bastard on blockade runner, Obi-Wan Kenobi, unnamed X-Wing pilot, Red Leader, Biggs Darklighter and the three Y-Wing pilots who look like high school principals
• Episode 5: Two — Admiral Ozzel, Captain Needa
• Episode 6: One — The Emperor
Vader, of course, is a sadist, not a mathematician, so he's not one to keep score. But even he would have to admit his reputation for brutality is largely unearned. He goes into a total slump in The Empire Strikes Back and Return of the Jedi, killing no Rebels at all! That's not an elite Sith.
It's his offspring who is the real problem. Maybe all these rumors about Luke going to the Dark Side in Star Wars: The Force Awakens are onto something.