Since Cesare Lombroso’s days, criminology seeks to define, explain, and categorize the various types of criminals, their behaviors, and motives. This aim has theoretical as well as policy-related implications. One of the important areas in criminological thinking focuses chiefly on recidivist offenders who perform large numbers of crimes and/or commit the most dangerous crimes in society (rape, murder, arson, and armed robbery). These criminals have been defined as "habitual offenders," "professional criminals," "career criminals," and "serial offenders." The interest in these criminals is a rational one, given the perception that they present a severe threat to society. The main challenge in this area of research is a conceptual problem that has significant effects across the field. To this day, scholars have reused and misused titles to define and explain different concepts. The aim of this article is 3-fold. First, to review the concepts of criminal career, professional crime, habitual offenses, and seriality with a critical attitude on confusing terms. Second, to propose the redefinition of concepts mentioned previously, mainly on the criminal career. Third, to propose a theoretical model to enable a better understanding of, and serve as a basis for, further research in this important area of criminology.