Have you ever seen something on a TV show that you can't shake off? Ever witnessed a moment that's totally floored you?
Here are some of the TV scenes that have done just that to us – brutal, shocking sequences that we're still haunted by.
1. Gus and the box cutter - Breaking Bad
Eerily Zen-like in his calm, Gus Fring was Breaking Bad's most quietly menacing character. We knew he was ruthless, but until season 4's premiere we didn't know he was capable of such maxed-out brutality.
When he pulls out the box cutter knife in front of a tied-up Walt and Jesse, it looks initially like an empty threat, something to simply scare his two chemists into submission. Until, that is, he puts on a hazmat suit and, in a flash, slices open the throat of his loyal henchman Victor.
Calmly, he then takes off the suit and walks away, telling them, "Get back to work." 'Don't mess with Gus' is the clear message here.
2. The killing of Combo - This is England '90
Combo (Stephen Graham) had spent much of the eight years between This is England and the saga's small-screen finale making amends for his savage attack on Milky (Andrew Shim). By This is England '90, he'd found God and and was working with disabled teenagers.
But Milky had long been planning his revenge, and after a face-to-face between the two where Combo offered him a heartfelt apology, Milky's mates arrived to take Combo away. His fate was sealed, and we last saw him in a derelict warehouse, begging for his life.
Combo started out as This is England's greatest monster, but by its end was one of its most decent, morally healed characters. As he was bundled away, screaming "I don't wanna die, I don't wanna die", it was a gut-wrenching sight. We didn't see the moment of his death, but our imaginations were able to fill in the blanks.
3. Jessica Raine is thrown out of a hospital window - Line of Duty
In all the publicity for Line of Duty's second series, Jessica Raine, then riding high on the success of Call the Midwife, was being talked up as a regular, a brand new partner for Martin Compston's Detective Sergeant Steve Arnott.
But it was a classic piece of misdirection. Detective Constable Georgia Trotman didn't even survive the first episode, being pushed out of a hospital window while attempting to stop a murder. "I always had her in mind as a character who would die at the first episode," said writer Jed Mercurio. "I wanted the first episode to end with a shock."
4. The wedding massacre - Dynasty
Twenty-eight years before Game of Thrones' 'The Rains of Castamere', glittery soap opera Dynasty had its own 'red wedding' with its most breathlessly exciting cliffhanger.
Remember, this was a soap which people turned on to wallow in its designer outfits and six-star living. If violence did crop up in Dynasty, it was more likely to be two ladies yanking each other's hair extensions out than anything bloody.
But in 1985, the wedding between Blake and Alexis's long-lost daughter Amanda (Catherine Oxenberg) and Prince Michael of Moldavia (Michael Praed) ended in carnage. Midway through the ceremony, terrorists smashed their way in and sprayed the chapel with bullets.
By the time the final credits rolled, it looked like everyone was dead. Of course, the next season revealed that virtually everyone had survived. But a limp resolution doesn't take away from the power of that stunning final image.
5. Lisa Faulkner gets battered - Spooks
Again, from all the pre-publicity for BBC One's flashy new spy series Spooks, it looked like Lisa Faulkner, as the biggest name in the cast, was in it for the long run. But then, in only the show's second episode, she suffered a death that's still burned (no pun intended) into the memories of all who saw it.
Kidnapped by a racist thug, her character Helen Flynn had first her hand and then her head pushed into a deep fat fryer, before a bullet put her out of her misery. It's enough to put anyone off their fish and chips.
6. The peeing lady - Threads
We could put all 112 minutes of this unremittingly bleak TV play about a nuclear war and its effects on Sheffield in this list, but the most powerful, memory-searing moment comes when the bomb goes off over the South Yorkshire city and a middle-aged lady pees herself in the street. It's a beautifully simple demonstration of utter, sphincter-slackening terror.
7. Glenn's grisly death - The Walking Dead
Having just (rather ludicrously) survived a zombie onslaught, it looked as though The Walking Dead's Glenn (Steven Yeun) had more lives than Kenny from South Park and might outlive even Rick (Andrew Lincoln).
But no, he finally bit the big one in the opening moments of the episode 'The Day Will Come When You Won't Be' in 2016.
And what a way to go – you wouldn't wish such a gruesome demise on your worst enemy, with Glenn having his head smashed in with a barbed-wire-wrapped baseball bat wielded by psychopathic Negan (Jeffrey Dean Morgan).
The eye popping right out of his skull was a particularly gruesome detail that we're still having trouble shaking off.
