Star Trek series were generally aired during a family-viewing time (i.e. after five but before nine). Can't speak for the other series, but with TNG throwing out several episodes dealing with heads blowing up, heads being blown off, human laboratory experiments, bloody death scenes, psychological and physical torture (that were advised on by the folks at Amnesty International) and let's not forget the Borg ... you have to wonder whether this was always a good idea.
And in TOS alone there's plenty of this. How about the episode "The Paradise Syndrome" where Kirk gets married to a woman, gets her pregnant, and then she gets stoned to death. On camera. Yeah.
"Miri", with its facial disfigurement, homicidal mania, and children under threat, caused a big row in the UK when it was first broadcast. This led to it and three other episodes being left out of UK showing of the series until the 1990s.
In the opening moments of DS9, we saw Jennifer Sisko, trapped under debris, dead or dying, the room burning around her as her husband desperately tried to reach her. By season five, they were including scenes of Starfleet officers dying from gruesome injuries. And then there's the Dominion War...
In a similar vein, Enterprise's "Unexpected" is also about rape as a joke. It falls somewhere between date rape and child molestation. Sure Trip's an adult, but the lizard lady's dialog just screams "I've got candy in my van". Calling her sexing up of Trip "a game we play" when he doesn't know what's happening.
Lets not forget Deep Space Nine's "The Siege of AR-558" which features the Dominion's shock troops attempting to reclaim a communications outpost that had been seized months earlier by the Federation. The Defiant shows up to provide supplies at first, but the crew remains behind when The Jem'Hadar sneak attack Nog and they realize a siege is inevitable. He winds up losing a leg due to that and what follows is a quite violent fight against a horde of shock troops, all while classy jazz music plays, thanks to Bashir having a recording of Vic Fontaine singing.
Charlie X features the titular character, who can be summed up as Anthony FreemontIN SPACE, and with even worse fates for anyone who crossed him (at least Anthony's victims were Released to Elsewhere after their transformations). Oh, and he blew up a ship, stalked a yeoman and killed her when she slapped him, and made Spock recite poetry. And the race that adopted him terrifies him, to the point where he's begging the same people he was just bullying not to let them take him away.