- Kandron of Onlo is responsible for the worst of it, in Children of the Lens. When Nadreck investigates him, he compiles a file of roughly a thousand cases of hitherto respected and admired citizens suddenly committing the most unthinkably savage and sadistic violent crimes (due to Kandron's brainwashing). The description includes summaries of a few of them, which are probably enough to give sensitive persons nightmares.
- The Delgonian Overlords are almost certainly objectively worse than Kandron, though their activities are thankfully not described in much detail. What they do to Kinnison in Gray Lensman, though, almost matches him at his worst.
- The brief but haunting description of how the minds of the Overlords' surviving victims work after they have had their way with them in Children of the Lens makes their routine procedures at least as horrifying as anything Kandron ever did.
- Herkimer Herkimer's treatment of Jill Samms in First Lensman. Not quite up to the standards set above, but made worse by the fact that unlike the people in those entries, he is not a monstrous alien, but a human (and Faux Affably Evil) psychopath.
- Kinnison's experiencing a planet subjected to Boskonia's covert subliminal propaganda campaign. It's fast-acting enough that he can observe in real time how the planet goes from a happy and prosperous modern society to a Crapsack World under martial law and on the verge of imminent breakdown, as more and more its population goes crazier and crazier.
- On a more "realistic" scale, the description of one of Boskonia's Space Pirate subcontractors massacring one of the Patrol's hospital ships in Galactic Patrol. It's not especially lurid or even graphic by modern standards, but it rams home very effectively the horrors of fighting a war against an utterly lawless enemy.
- Similarly, what can be deduced of Illona of Lonabar's life in Boskonia from her debriefings after the Patrol captures her — And by implication, what life for most people in Boskonia may well be like. Again, Humans Are The Real Monsters. This one probably also qualifies as a Tear Jerker.
Nightmare Fuel / Lensman