The Major Crimes Unit deals with elaborate and/or unusual crimes (and criminals) that would too heavily burden the city's day-to-day police operations, with high-profile crimes, with professional career criminals with a history of violence, and with criminal fugitives.
- Dick Tracy
- Sam Catchem
- Lizz Worthington Grove
- Lee Ebony
- Johnny Adonis (Former)
- Det. Frisk (Former)
- Lt. Teevo (Deceased)
- Ms. Steffihawk, Reception
- Junior Tracy, Sketch Artist and occasional operative
- Groovy Grove, uniformed patrolman often detailed to MCU (Deceased).
- Many real-life cities, including New York and St. Louis, have Major Crime Units in their police departments. These are sometimes referred to as a Major Case Unit or Squad.
- In the real-life Chicago Police Department, there was once a special unit called the "Scotland Yard Detail," which dealt with similar high-profile crimes and municipal corruption. Later, there was a Central Investigations Unit (fictionalized on the TV series Crime Story as the Major Crimes Unit) that targeted violent career criminals, as well as major robberies and burglaries. Today, there is a Major Case Unit and a Fugitive Unit. The Major Crimes Unit in the Dick Tracy comic strip is a synthesis of all these real-life special details.