Red Shirts
Ever heard of the term “Red-shirting?” It became Star Trek slang for an extra who was killed to demonstrate the danger that the main characters were in. Those extras almost always wore a red uniform.
Source: Inverse
As a tribute to the original series’ “red-shirting,” Chief Engineer Olsen in Star Trek (2009) wore a red shirt when he met his death during an orbital skydive onto a drilling platform. Kirk and Sulu, however, survived.