Defendants face charges including participating in a criminal organisation and causing life-threatening explosions at sporting events, with seven accused as alleged group leaders.
Marinakis and four board members are accused of supporting the alleged criminal group and instigating violence between 2019 and 2024, charges they deny as groundless.
The probe was initiated following the fatal injury of 31-year-old riot police officer George Lyngeridis in 2023 during clashes outside a women's volleyball match.
The trial, which began on Wednesday, is expected to involve over 210 witnesses and could potentially last for several years, marking a significant crackdown on hooliganism.