This chapter discusses several special populations within the juvenile justice system, including school shooters, mentally ill juvenile offenders, juvenile drug and sex offenders, chronic juvenile offenders, hackers, violent juvenile offenders, and hate crime offenders. School violence increased in the 1990s with shootings like Columbine but zero tolerance policies have since improved school safety. Mental illness is common among incarcerated youth, with 1 in 5 suffering from a serious disorder like conduct disorder or substance abuse issues. Chronic juvenile offenders begin criminal behavior early and persist into adulthood. Violent juvenile offenders often start young and become chronic violent offenders over time. Hate crimes are committed against individuals due to attributes like race, religion or sexual orientation, and are perpetrated by members of traditional