The Agents of S.H.I.E.L.D. episode "The Girl in the Flower Dress" features Debbie, a scientist for the mysterious Centipede project, getting roasting alive onscreen, screaming before she turns into a blackened, decaying skeleton. It was slightly toned down for Channel Four pre-watershed airings in the UK, but was still pretty horrific.
In "Spacetime", Gideon Malick crushes a business man's head in very graphic detail.
SuperMagic PowerMan and Lanolin Lady in The Aquabats! Super Show! episode "Showtime!" are vaporized using SuperMagic PowerMan's magic headband worn by the young girl they just saved, who turns into Space Monster M.
Caleb's death - bisected from the groin up. Being a psychotic, misogynistic serial killer seems to make this acceptable viewing, however.
Spike's Dying Moment of Awesome (he gets better) — being burned alive from the inside out. It's awesome by virtue that he took an entire army with him, but watching his skin shrivel and burn is pretty horrifying.
Warren gets flayed alive onscreen, which is the second most gruesome moment in the show (first being when Gnarl eats Willow's skin). And like Caleb, he was a psychotic misogynist who deserved it. At least Caleb being chopped in half was somewhat offscreen. Even worse with Warren is when he returns in the Season 8 comics as a body with no skin.
CBS Schoolbreak Special: The 1984 episode "Dead Wrong: The John Evans Story," the true story of a death row inmate who went on a crime spree that ended with the murder of a pawn shop owner, shows at the end a very chilling electric chair execution (a re-enactment) of Evans for his crimes.
The shooting of the pawn shop owner – watch for a young Nicole Eggert here – during a robbery is also chilling, and the reaction of his two daughters is truly scary and heartbreaking to watch.
The real-life execution of Evans is even more family-unfriendly than depicted on TV, however. The real-life execution reportedly required multiple shocks, and there were written accounts claiming that he was still alive after the first two shocks. There were also claims of flames and smoke coming from the leg electrode and from beneath the hood concealing his face. On the TV version, the final scene simply shows the unconscious Evans sitting in the chair, with no references to the imprecisions that occurred.
Two fairly notorious examples from the classic episodes would be a guard falling into a pool of acid in "Vengeance on Varos" (mostly notable because the Doctor seems to make a mean-spirited quip about it afterward) and Kane, the low-temperature-lifeform villain in "Dragonfire", exposing himself to direct sunlight, resulting in his face melting off, Raiders of the Lost Ark-style (one of the few occasions on which the series' special effects managed to be memorably gruesome).
"The Daleks' Master Plan" has an unusually graphic ending for Who — the Daleks activate a time-altering superweapon which almost kills the Doctor, and ages the Doctor's companion Sara from a beautiful young woman into an old woman, then into a mummified corpse, a skeleton, and then to dust. Steven then puts the weapon into reverse, which causes the Daleks to de-age into foetuses, which eject from their cases, flop about and die. The Doctor even picks up one of these foetuses and laughs about how great it is that he's wiped out every Dalek on the planet, leading to a What the Hell, Hero? moment from Steven.
The death of beloved companion Clara Oswald in "Face the Raven" resulted in complaints being lodged against the BBC by parents who felt it was too disturbing for younger viewers (in part because it was the first time in more than 30 years that a companion had been killed in a violent fashion).
Although he didn't die per se, In "DNA Mad Scientist" we're treated to an incredibly painful Transformation Sequence as Namtar rapidly devolves from his sentient and heavily genetically modified state, back to the lab critter he was originally. And it's all done on-screen.
"A Bug's Life" features an intelligent virus which hijacks its host, and proceeds to commit gruesome murders. In one case, Crichton, while possessed, crushes a female Peacekeeper's skull with a piece of Zhaan's laboratory equipment by bludgeoning her repeatedly.
Br'Nee is cut in half with his own shrinking ray in "Bone to be Wild" and we get to watch his lifeless corpse twitch. Not to mention what it's implied Em'Lee does to her victims after Scorpius "rescues" her...
While a favorite among Crichton/Aeryn shippers because of its strong romantic plot, the "Look at the Princess" trilogy has several: Prince Clavor has his face melted by the Scarran Ambassador, who himself is later dumped into a vat of acid. The Empress's servant, who has betrayed Crichton to Scorpius, gets tossed into a high-voltage panel and electrocuted, causing her skin to split open and blood to pour from the wounds.
Crichton blows the head off another Scarran by jamming an overloaded pulse pistol in its mouth.
The fate of the Peacekeeper test pilots unfortunate enough to be chosen by Scorpius in his wormhole experiments: Reduced to liquefied goo. We don't see their deaths on-screen, but we do see the gooey results. Linfer suffers the same fate and we actually see her begin to liquefy.
Aeryn's old friend in part two of "Into the Liar's Den" gets her face burned off as Scorpius's Command Carrier explodes around them. We watch her stumble forward a few paces, gasping for breath before she finally collapses and dies.
The deaths of D.K. and his wife at the hands of Skreeth: We don't see the fatal blow, but we do get to see them tortured first.
Bioloid!Aeryn gets a gaping hole blown in her face by Crichton when they discover the switch.
Hynerian Dermafolica is not a pleasant way to go.
Gimme a Break!: One of the earliest episodes of this 1980s series, "Your Prisoner is Dead," depicts Carl shooting a robber in self-defense; the suspect dies at the hospital, and Carl — explaining to his daughters and Nell that he had been placed on administrative leave while the investigation ensues — tells Samantha that the robber did not die a bloodless death, and likely felt pain in his final moments, a stark contrast to what they had seen on television.
The Great Space Coaster: An early episode showed a live-action clip of a man pulling a drain plug, and the suction pulled everything in sight, including people, into the drain, until all existence is wiped out! Played for laughs, of course.
Kamen Rider Ryuki introduces Kamen Rider Scissors/Masashi Sudou who gets a particularly memorable send-off when he is eaten alive by his own Mirror Monster.
The titular rider gets himself stabbed in the back in the penultimate episode, complete with Blood from the Mouth
Not to mention Kamen Rider Ohja getting gunned down by dozen of police.
While their deaths aren't actually seen, Kenan and Kel, in "Two Heads Are Better Than None", find three severed heads on a table. Of innocent victims. Who had been previously introduced.
Monk is generally a PG-rated, family-friendly show, but the pre-credits sequences often feature gruesome and disturbing death scenes. Usually, ones that involve blood.
The Muppet Show: A large monster eats a smaller, cuter monster while singing a very eerie version of "I've Got You Under My Skin" to his victim. Did the person who came up with that gem have a vore fetish or something?
Even worse is the glowworm sketch, which involves a lizard-esque creature sits on a wall while humming a tune ("Glow Little Glowworm") and eating worms that poke at him until it bites a worm that's actually the nose of a bigger monster that proceeds to eat the lizard. If only Jim knew that people would take that sketch in a different way decades later.
The Swedish Chef was strangled by his own spaghetti bolognese.
And beaten by a sentient pile of dough, shot by a turtle, hit in the head with his own cleaver...yikes.
Frax's death in Time Force was a Dies Wide Open involving a scream and parts of his robotic face falling apart. This after his having been reprogrammed into a mindless automaton by the Big Bad. (And this after having been human once.)
Believe it or not, Wild Force was the first Power Rangers season to show blood. (As a plot point, nonetheless. The blood dripping from Zen-Aku's hand indicates he isn't a normal Org, as Orgs don't have hearts and therefore can't bleed.) In another episode where Alyssa is attacked and Zen-Aku tends to her wounds she has a bloody scrape on her leg.
Flashbacks showed vines assault and grow through the bodies of two terrified humans. Apparently, a bloodless death can't possibly disturb anyone.
They actually only got away with this one due to a Channel Hop. They told the first network (Fox) that the characters would later turn out to have survived, which makes it okay somehow. They then "neglected" to tell the second network (Disney) that the death had ever happened, so they didn't have to keep the promise, and they stayed dead.
Also, one Monster of the Week, while the Orgs were trying to convince Animus that humans weren't worth protecting because they ruin the Earth, attacks a construction site. "Humans destroy the Earth! I DESTROY HUMANS!" he declares, firing a blast of fire. We zoom in on some terrified workers, and... boom! Mind you, the final 'boom' is shown through the not-terribly-clear pool on the Animarium that serves as this year's 'viewing globe.' But still. Incidental civilians that the plot didn't need to actually die... actually die. By a blast of flame.
Ninja Storm had a cyborg villain suffer melting at the hands of another, treacherous villain. His half-slagged body is seen in a rare exception to PR's Everything Fades tendency. His executioner quips that he was "having a little meltdown".
Ninja Storm has one that wasn't the death itself, but... the monster of the week was a pig. The Rangers beat him, he goes giant, they beat him again, he explodes... and then we see Lothor eating his barbecued remains; the other villains were as disgusted as should be expected.
A rather nasty, Mecha-Mooks loophole exploiting death in Zeo where two groups of enemy mooks have a battle royale. The mooks are Tengas (bird men) and Cogs (spandex robots) You see Tengas and Cogs sluggin it out for a few shots, then it cuts to one Tenga holding down a struggling Cog while another Tenga tore open its stomach and ripped out its electronic guts. This wasn't Chouriki Sentai Ohranger footage that slipped past the censors, either - Tengas were Power Rangers-exclusive mooks, so it was all original footage. (Also, Tengas are hatched from eggs and explicitly alive. This makes the ones who were on the ground and not moving at all explicitly dead.)
Oh my goodness, Zeo. Louie Kaboom, the temporary leader of the Machine Empire. Under a love spell cast by the new villains he takes on the Rangers in combat, and is eventually defeated. However, unlike most of the mindless minions that fell to the Rangers, he remained alive for a few moments, stumbling around in pain while on fire and professing his love for the villain that brainwashed him.
Super Sentai was far worse when it came to this. Especially in the early 80s. In the first episode of Denshi Sentai Denziman, for example, construction workers are skeletonized into piles of sludge and bones.
We also get to see some of the grunts in Flashman gooify some victims. This happens much less often in the newer series; though Super Sentai doesn't suffer from America's Never Say "Die" problem, if grunts assault random civilians, the random civilians usually aren't explicitly subjected to melting, etc. onscreen. Not so the earlier series.
Sesame Street: Narrowly averted in an early episode, where — after he devour everything in sight — Cookie Monster attempts to eat Kermit The Frog. Cookie shows some mercy, however.
Through the Dragon's Eye, a 1990s kids' educational series for schools, featured an anthropomorphized quagmire which would merrily drag cast members down to their doom. And this was used in a cliffhanger.
The Big Bad, who happens to take the form of a sort of skeletal bird with an exposed ribcage, wrapped in a black cloak and with Freddy Krueger-style scissor fingers, actually melted several of the secondary characters. Seriously. Into pools of liquid...
They got better. But not until right at the end, weeks later. And kids were actually required to watch this in classes.
Many of the aliens in Ultra Seven were killed by Seven with the Eye Slugger, meaning they were chopped into pieces on-screen. So you got a lot of beheadings, aliens being sliced in two, monsters getting their arms chopped off, and that sort of thing. Perhaps the most gruesome death was from "Super Weapon R-1", where Ultra Seven kills the mutant alien Gyeron Starbem by tearing off one of its bladed arms and using it to slit the monster's throat.
Many of the monsters in Ultraman Taro exploded when killed as per Ultraman tradition, but rather than the typical vaporization of the body, there were Ludicrous Gibs involved.
Take Ultraman Taro and Ultra Seven above, combine them, and take it Up to Eleven and you have Ultraman Ace. Perhaps the most memorably graphic was the death of Muruchi, in which another monster called Doragory kills by tearing Muruchi into pieces. On-screen.
To make matters worse, monsters weren't the only victims of the trope. In Ultraman Ace, the acid-spitting insect monster Aribunta turns an entire subway of screaming people into skeletons, and in Ultraman Taro, Taro is stabbed to death by the avian monster Birdon, complete with grisly wounds left by Birdon's beak in Taro's skin (don't worry, he gets revived later).
Zoom. Jittery, terrified talking paper collage vegetables in a garbage disposal, waiting and waiting for the horrific moment when the memorably nasty-looking blades would start spinning and puree them all.