Fictional viruses are imaginary pathogens created in literature, film, and video games. They often serve as plot devices, driving the story forward by causing chaos or prompting characters to find a cure. Examples include the T-Virus from the Resident Evil series and the Green Flu from Left 4 Dead. These viruses can exhibit unique characteristics, such as transforming humans into monsters or spreading rapidly through the air. They allow creators to explore themes of survival, morality, and the consequences of scientific experimentation, engaging audiences with thrilling scenarios and ethical dilemmas.