Spooks – I Spy Apocalypse (2003)

The episode starts with the Spooks team locked down while undergoing a drill relating to a hypothetical terrorist attack, overseen by two Home Office officials, but as things progress it appears that there really has been an attack and a chemical weapon has been unleashed. The tension ratchets up as incoming communications show a catastrophe taking place outside, and gets worse as the boss appears to be infected, and the two Home Office officials attempt to leave, forcing Matthew Macfadyen’s character to decide between shooting them, or letting them go and risking contaminating the sealed MI5 offices. This being Spooks, it is unsurprising which one he chooses. **Paul, Sheffield **

Threads (1984)

Absolutely terrifying … Victoria O’Keefe as a survivor in the ruins in Threads. Photograph: BBC Archive

Threads was low budget but one of the most frightening programmes I’ve ever seen because of the stark reality and grim official statistics. Watched it about a month ago having watched the original; I used to visit the pub in Sheffield from the programme which emphasised the reality and the glib matter-of-fact official information which was broadcast. Still absolutely terrifying 35 years later. John Bradbury, Ilkley

Severance – The We We Are (2022)

Like an eruption! … Severance. Photograph: Apple

The season one finale of Severance has to be right up there. I spent the entire episode quite literally on the edge of my seat, straining every sinew with Dylan to keep his hands on the levers that kept the Innies on overtime, while screaming at the Innies to get their truths out there. The final climactic moment – “she’s alive!” – was like an eruption. **Keith Wilkinson, Stokesley, North Yorkshire **

Industry – White Mischief (2024)

Had my heart racing … Sagar Radia and Asim Chaudhry in Industry. Photograph: Nick Strasburg/BBC

Episode five of the third series of Industry had my heart racing. I had to pause and get up and leave the room several times because of the sheer scale of the wanton self-destruction I was witnessing. Rishi Ramdani is in deep shit at work and home – up to his eyeballs in debt to loan sharks because of his compulsive gambling, taking such risks with a bet on sterling which could lose his company millions. So of course, he goes on a gambling spree, does tons of drugs and drink and wins, loses, wins, gets beaten to a pulp. Every time you think it can’t get any worse, it does. There’s hope of redemption at the end of the episode but he squanders the opportunity, with horrifying consequences in the season finale. Definitely needed a lie-down after that! **Tania, London **

Peep Show – Holiday (2007)

So cringe you’ll end up riddled with anxiety … Robert Webb as Jez in Peep Show. Photograph: Channel 4

Peep Show itself isn’t necessarily a stressful show. But the episode Holiday contains such levels of cringe that it’ll have you standing up the whole episode, riddled with anxiety. It all ramps up once Jeremy and Mark find themselves having to lie about the dog they accidentally run over and subsequent attempts to dispose of it. You then spend the rest of the episode questioning whether it truly can be worse than incineration, and it can be! Dan, Canberra, Australia

The West Wing – The Two Cathedrals (2001)

Wonderful television, never bettered … Martin Sheen in The West Wing. Photograph: PictureLux/The Hollywood Archive/Alamy

Nothing I’ve watched has been more intense than the first time I watched the season two finale to The West Wing. The episode starts with the aftermath of the death (in a traffic accident) of the president’s personal secretary and reaches a crescendo with a crisis in Haiti, and the fallout from the non-disclosure of the president’s MS diagnosis, with confirmation of his intention to seek re-election. Wonderful television. Never bettered. **Ian, Surrey **

Bodyguard – episode one (2018)

The tension is unbearable … Richard Madden and Keeley Hawes in Bodyguard. Photograph: Everett Collection Inc/Alamy

The opening of the British series, Bodyguard, with the protagonist on a train with his young son is for me one of the most intense episodes ever. He spots a Muslim woman going into the loo and knows something is off. The bomb diffuser experts are called, board the train, and attempt to convince the woman to take off her suicide vest. Tension escalates to an almost unbearable degree, until yes, the vest is diffused.Heather MacAndrew, Victoria, Canada

Buffy the Vampire Slayer – The Body (2001)

Total shock … Buffy the Vampire Slayer. Photograph: BBC

Buffy enters her house to find her mum has passed away of natural causes, which is the most unusual type of death in this supernatural show. The episode has no background music, a sullen tone, and we see the episode through the experience of Buffy’s shock of discovering her mother. Ruth, Wales

The Sopranos – Made in America (2007)

My heart dropped from my mouth 20 minutes later … James Gandolfini, Edie Falco and Robert Iler in The Sopranos. Photograph: Will Hart/HBO

The final scene of the final episode of the show was pants-wettingly tense. And if you watched it when it originally aired, you – at first – weren’t sure why. Tony’s enemies, real and imagined, were all vanquished. Surely this has the feel of the season one ending? “Remember the little things.” But the mood is bizarrely ominous. Almost Twin Peaks levels of terror. The family sit in a restaurant. Meadow parks. Tony sadly tells Carmela there’s trouble afoot with yet another of his crew working with the government. Meadow parks. Strange people enter the restaurant. Stare at Tony(?) Meadow parks. Tony puts a record on the jukebox. Meadow parks. The bell rings, someone enters the restaurant. Can’t be Meadow, she’s still parking. Tony looks up. Don’t stop. It stops. My heart dropped from my mouth about 20 minutes later. **Paul Wilson, Hebburn Tyne and Wear **

The Walking Dead – The Last Day on Earth (2016)

What a cliffhanger … The Walking Dead. Photograph: Gene Page/AMC

I stayed up to watch this episode at 2am. It was so intense after the buildup of bad guy Negan finding the group, cruelly taunting his victims then not knowing who he killed (ended on a cliffhanger). The victim’s POV shot and the muffled sounds – argh! We then had to wait for season seven for the outcome. Great watercooler TV but sadly, the show was never that good again. **Louise Wright, Manchester **

Babylon 5 – Severed Dreams (1996)

Utterly compelling … Babylon 5. Photograph: PR

The Earth civil war comes to a head as loyalist forces head to the station to take over and arrest the command staff. The battle sequences hold up but the sheer weight of the stakes involved and the performances by Bruce Boxleitner and especially the late Mira Furlan are utterly compelling. Creator J Michael Straczynski originated the term “Wham Episode”, and this one delivers both in terms of building suspense when the opposing forces square off and at the end when the dust has settled you’re not left with a feeling of victory but instead the biggest “well what now?” of the show’s run. It gives me goosebumps even 30 years later. Greg, Merseyside

The Killing (Danish version) – episode 19 (2007)

An absolute masterpiece … Sofie Gråbøl in The Killing. Photograph: Nbc/Sportsphoto/Allstar

The first series of the The Killing (Danish version) is an absolute masterpiece, which spawned many a copycat and yet to be matched. Every episode ended on a massive cliffhanger, but episode 19 when Sara sees Vagn’s T-shirt and realises who the killer is gives me chills every time. Marcela, London