Warning: This article contains US-pace spoilers for Game of Thrones that some readers may prefer to avoid.
SERIOUSLY: Do not read on if you haven't watched 'The Children' yet - or you only have yourself to blame!
"Once a cheater, always a cheater!" - Rachel Karen Green, September 25, 1997
We might live in the age of the TV anti-hero - with theft, deception and even murder often considered par for the course for our protagonists - but one sin that remains simply beyond the pale on television is cheating.
So while Tyrion Lannister (Peter Dinklage) was hit hard when his beloved Shae (Sibel Kekilli) betrayed him at his trial, the revelation that she'd been sleeping with his father Tywin (Charles Dance) - the lusty lion - was on a whole other level.
With her worst secret exposed in last night's Game of Thrones season four finale, Shae joins the dubious ranks of TV's biggest cheating scoundrels - debauched philanderers and heartless harlots, the lot of 'em.
1. Tony Soprano from The Sopranos
James Gandolfini's mob boss was, amongst his many other crimes, a persistent love rat - from prolonged affairs, to fondling dancing girls to lusting after his therapist Jennifer Melfi (Lorraine Bracco), Tony Soprano just couldn't keep it in his pants.
His enraged reaction then to the flirtation between his wife Carmela (Edie Falco) and his enforcer Furio (Federico Castelluccio) was every bit as hypocritical as it was explosive.
2. Don Draper from Mad Men
He might've had the comely Betty (January Jones) waiting at home, but the self-destructive nature of '60s stud Don (Jon Hamm) drove him to cheat on his wife on countless occasions.
Draper took artist Midge (Rosemarie DeWitt), his glamorous client Rachel (Maggie Siff) and even his daughter's teacher (Abigail Spencer) into his bed - and it's clear he hasn't learnt his lesson, with his second marriage to Megan (Jessica Paré) plagued with more infidelities.
3. Peter Florrick from The Good Wife
Lest we forget, it was Peter's involvement in a sex scandal that set the entirety of The Good Wife into motion - his marriage to Alicia (Julianna Margulies) took a serious hit after his sordid affair with a prostitute and was further tested when she returns to the legal profession and found herself drawn to old flame Will Gardner (Josh Charles) - now her boss.
4. Marty Hart from True Detective
Affable on the outside but harbouring a tortured soul, Woody Harrelson's complex cop Marty Hart in HBO's True Detective was catnip to the ladies of Louisiana - but his marriage to Michelle Monaghan's Maggie was effectively ended by his affair with court reporter Lisa Tragnetti (Alexandra Daddario).
Still, Maggie got her own back by seducing Marty's brooding partner Rust (Matthew McConaughey) - leading to an almighty dust-up between the two detectives.
5. Lori Grimes from The Walking Dead
Alright, so she thought her husband Rick (Andrew Lincoln) was dead, but taking comfort in the arms of his best friend Shane (Jon Bernthal) remains a major misstep on the part of Lori Grimes (Sarah Wayne Callies) on The Walking Dead.
The indiscretion sparked much resentment between Lori and Rick and she eventually fell victim to the harsh wilderness that is a zombie dystopia before they could patch things up.
6. Gwen Cooper from Torchwood
She might be the heroine of much-missed Doctor Who spinoff Torchwood, but Gwen Cooper (Eve Myles) certainly got about a bit - even putting aside her professed love for John Barrowman's Captain Jack, her romping with Burn Gorman's laddish medic Owen Harper was a slap in the face for poor hapless fiancé Rhys (Kai Owen).
She did come clean to her future husband, but later used an amnesia pill to erase his memory of the confession - escaping the whole affair consequence-free. Still, compared to serial shagger Jack, Gwen's a beginner.
7. Spencer Matthews from Made in Chelsea
One of the worst offenders on this list isn't even fictional - the indiscretions of Mr Matthews on E4's Made in Chelsea are made all the worse for the fact that they're 100% genuine and definitely not made up even a bit, honest.
Across seven series, shameless Spenny has slept his way around SW3 something fierce - cheating on three girlfriends, betraying best buds and rarely displaying even a smidgen of shame or regret. He even took part in a drunken "orgy" a couple of weeks back - though he was at least single on this occasion.
8. Ross Gellar from Friends
Oh Ross, you're not a bad sort, but even 17 years later, we can't forgive you for making out with the hot Xerox girl. Break or no break, hooking up with some random chick mere hours after a relationship ends is a dog move - as Chandler noted: "Bullets have left guns slower!"
Who else deserves a damning spot on our list of TV cheaters? Share your own picks below!