9. The Kray Brothers

These twins are definitely the most notorious on the list. The Kray Brothers became well known for being the perpetrators of organized crime during the 1950s-1960s in the East End in London. Ronnie, a paranoid schizophrenic, and Reginald lived a life of violence, often participating in arson, torture, assaults, armed robberies, and murdering many, including George Cornell and Jack McVitie. Despite their violent and crude nature, the twins could be found spending time with very popular entertainers such as Judy Garland and Frank Sinatra. In 1968, the twins were arrested and sentenced to life imprisonment and have both since died.