FTL: Kestrel Adventures: Whilst the series is based off of a real playthrough of FTL: faster than light, no-one has died yet. However, it is extremely likely that many characters can die in later episodes.
In The Gamer's Alliance, a number of heroes and villains, including very prominent ones, have been killed off for real, some more dramatically than others.
Hero House is a strong example. In season one alone they've lost Superman, Batman, Robin and Nightwing!
KateModern has unexpectedly killed off a few major recurring characters, often midseries, quite casually, and with bodies shown so that we know they aren't just hiding. It also once killed off a central character offscreen, with no fanfare, as a major plot point.
The Legatum series zig-zags this trope, depending on the theme and tone of each story.
Smirvlak's Stone kills off every major character exceptGnekvizz, who just so happens to be the main villain.
Scrambled Egg kills off everyone except for Snorrv and Synnyk Synncader.
A number of main characters in lonelygirl15 have been killed off unexpectedly, including lonelygirl15 herself.
The Pirates Covered in Fur kills off minor characters early on in the story, then starts picking off the main cast shortly after the story reaches the halfway mark. By the end of the story, nearly everyone is dead.
Although the situation was averted, one of the main characters came very close of dying in the imageboard adventure Ruby Quest. Weaver says he was prepared to kill him off had the players made any harsh decisions. It is likely that such situations might arise once again in the future.
Survival of the Fittest exemplifies this trope, being based off of Battle Royale. Of course, if you really want to get into the nitty gritty aspect of it, it's much more of a Kill 'Em All. This is doubly true in that the vast majority of deaths (or at least, when they are to occur) are determined randomly.
Tech Infantry killed off main characters, supporting cast, and Big Bads with abandon. Then came the Y3K Arc, which killed off pretty much every major legend in the TI Universe, before killing off pretty much everyone in the Galaxy.
While T.O.T. started off mostly humorous, the story still contained an absurd amount of mauve shirts, and someone ended up dying in almost every single chapter. Chapter 9 sees the death of the first main character, and by the time the story's over, less than five named characters are still alive.
Vinny makes it clear in playthrough of Tomodachi Life that he reserves the right to evict any islander he pleases. Most of the less interesting ones suffer, with special mention going to BonziBUDDY and Dolan, who were despised for their memehood and all but stated to have gone to Hell. It gets more a bit more straightforward with the Jahn Army's assimilation plotline, which several well-known islanders succumbed to. While it was partially averted in that the most prominent of the assimilated (Wario) was saved, it still caused Levi, Balegdah, and Jack & Jill, all of average notability, to be lost.
We're Alive has killed several minor characters including Bill, Tommy, and Samantha in season 1 and Kalani along with every Red Shirt Tower resident at the end of season 2. Angel died in season 3.
Normally, this trope is pretty much averted in the Whateley Universe. But it's front and center in the "Loose Cannons" storyline. Of the original twelve teenagers, five are already dead. And the story is only on its second chapter.
In Worm, a large number of minor and several major characters have been killed off. Even the protagonist's life was thrown to the whims of an eight-sided die, and the author made Plan Bs should she be killed off. Absolutely no one is safe.
In Everyman HYBRID, anyone can die at any time, like Jessa, Ryan, Jessie, Alex, Jeff, Daniel, Steph ...; well, except for Evan and Vin, despite both of them trying to.