Before there was a Red Wedding

There was The Transformers: The Movie, an animated feature from 1986.

Think I'm exaggerating by comparing it to Game of Thrones's Red Wedding?  Consider:

The Transformers tv show had run for two seasons prior to the movie.  The kids who watched it had grown attached to the protagonists.  The characters were animated robots, but they still had personalities, and that made them essentially human.  The kids all had their favorites.  None of the transformers ever died.  It was a "safe" show, right?

Then the toy company decided to promote a new line of transformers, and that apparently meant killing off the old ones.  That's what happens in the movie.  The Decepticons slaughter the first-generation Autobots.  They even kill the medic, man.  The medic!

Basically, the whole cast is turned over and shaken out, and what's left at the end is a bunch of strange robots the kids didn't know anything about.

Here's the shuttle attack where several Autobots are killed.

Later in the movie, more Autobots are killed in an attack on Autobot City.  Even Optimus Prime, that most beloved of transformers, would get killed off.

It was a brutal movie, especially considering the age of the target audience.