If you're a Family Guy fan who hasn't seen or doesn't want to know what happens in the latest episode, you might want to stop reading now.

Animated comedy Family Guy, now in its 12th season, isn't exactly known for its emotional depths and drama. Indeed, with its wacky, irreverent jokes and ever-changing internal logic, it's a programme that has barely changed since its 1999 debut. It even managed to survive its 2003 cancellation, returning two years later effectively the same as ever. Even more so than the likes of The Simpsons, it's a show that has almost constantly avoided multi-episode story arcs or narrative developments that can't simply be reset before next week's shenanigans.

This is why last night's new episode in the U.S. caught many viewers by surprise. In the episode, entitled Life of Brian, the Griffin family's talking dog Brian - voiced by series creator Seth MacFarlane since the show's pilot - was hit by a car and fatally injured. In a typical Family Guy episode, Stewie would simply have used his time machine to bring Brian back to life - but the episode emphasised that said machine was broken, seemingly irreparably. The credits rolled, therefore, without Brian being revived. Indeed, the writers even had the Griffins pick up a new dog called Vinnie, voiced by Soprano's actor Tony Sirico.

Speaking to E! Online, Family Guy's executive producer Steve Callaghan explained, "Well, this was an idea that got pitched in the writers room and it sort of caught fire, and we thought it could be a fun way to shake things up. As soon as this idea came up, we started talking about what the next couple episodes could be and we got very excited about the way this change will affect the family dynamics and the characters."

Whether Brian's death will be truly permanent remains to be seen, with some fans taking to Twitter vowing they will no longer watch the show if the episode's events are permanent. Callaghan says the next episode of Family Guy will be 'run-of-the-mill', suggesting Brian will, at the very least, be absent for a few weeks. 

In South Park, the writers once opted to kill Kenny for good (following the running gag that saw him killed off in every episode), but the popular character eventually returned. The Simpsons, meanwhile, has been more consistent when it comes to character deaths, with the likes of Maude Flanders dispatched for good, although it has only really been supporting characters permanently 'retired'. The Simpsons' writers, however, have already warned fans the current season will see the death of a popular character.