Star Trek used to have this tongue-in-cheek gag that saw officers wearing redshirts getting killed all the time. It's been rather overblown, as the number of red-shirted officers dying was far less impressive than the gag the fans embraced would have you believe. It took on a life of its own, however, to the point that one could call it the first Star Trek meme.
The redshirts, as they were dubbed, were members of the security and engineering portions of the USS Enterprise, as back in the 1960s on the original Star Trek series, red was for security and engineering, blue was science, and gold was command.
When Patrick Stewart joined up, it became obvious that they would have to switch things up for the sequel series, Star Trek: The Next Generation. It turned out that Stewart, according to legend, didn't like the gold, and with it becoming clear that Brent Spiner's Data was washed out by the red, the decision was made to make command red, security, and engineering gold and blue would remain the science and medical field.
Thus, the "redshirts always die" jokes died off, as it became less common to see command reds die in an episode. Yet, while it became less regular, compared to the 1960s series, it became more meaningful and dare I say, more noteworthy. See, when the series made the shift to The Next Generation, before including Deep Space Nine and Voyager, this thing started to happen to the captains of the ships; they started to die, or worse.
Jean-Luc Picard was abducted by the Borg, was braindead on a few occasions and nearly died at the hands of a nasty alien, all over gambling. Plus in Generations, he wound up in the Nexus, a pseudo heaven for people.
Benjamin Sisko would routinely be sucked into outer space to converse with wormhole aliens, seen as gods by the Bajoran people, thus making an argument that Sisko "died" and went to "heaven" whenever the aliens needed to talk to him.
The biggest example of the redshirt meme living on was Kathryne Janeway, who did end up dying several times during the course of Voyager. The most notable examples were at the end of the Year From Hell, and in the episode where Voyager was split in two, and one of the Voyagers and its crew had to blow themselves up to free the other Voyager.
There are more examples of course, and maybe even some better ones if you want to look deep enough but it's pretty clear that when Brennan Braga took over Star Trek, he maintained the status quo of making sure that redshirts still die.