There are many sub-genres of thrillers that vary slightly based on the specific elements incorporated into the narrative. Some common sub-genres include conspiracy thrillers which involve a protagonist confronting a powerful enemy, crime thrillers that focus on criminal activities like robberies and murders, and drama thrillers that have slower pacing and involve emotional development of characters. Other sub-genres are disaster thrillers centered around natural disasters, psychological thrillers dealing with mental conflicts, and religious or horror thrillers involving religious or frightening elements. Erotic thrillers incorporating erotic themes also became popular in the 1980s.