"Redshirts" refers to a trope in science fiction, particularly associated with the original Star Trek series. In the show, characters wearing red uniforms, often security personnel, frequently faced danger and were more likely to be killed during missions. This led to the term being used to describe expendable characters in various narratives. The concept highlights the idea of certain characters being introduced primarily to create tension or drama, knowing they are unlikely to survive. This trope has been referenced in many other media, becoming a shorthand for characters who serve to advance the plot but lack significant development.