Three prominent O.C. groups that i know of...

1.Italian mafia('Ndrangheta and Camorra)-Massive political corruption,church corruption,sport betting(mostly football corruption),narcotics(mostly cocaine and heroin),human trafficking(prostitution and immigrants),extortion,theft,weapons,kidnapping etc.Connections Eastern Europe,Great Britain,the Netherlands,Germany,Belgium,Switzerland,France,Spain,Czech Republic,Greece,Albania,Turkey

2.Russian mob-Massive political corruption,gas,oil,human trafficking(everything but mostly prostitution),weapons(every kind),hotels and casinos,sport betting,thefts,vast money laundering...Connections in France,Great Britain,Germany,Spain,Austria,Switzerland,Montenegro,Ukraine,Latvia,Cyprus,Turkey,Greece,Bulgaria,Czech Republic

3.Albanian clans-political corruption,religious corruption,human trafficking(immigrants,prostitution,human organs),narcotics(everything but mostly weed and heroin),weapons,thefts,kidnapping etc.Connections in Great Britan,the Scandinavian countries,Switzerland,Germany,France,Belgium,Italy,Balkans,Greece,Turkey etc. and also connections to terrosts groups like Al Qaeda.