Leonidas Phoebus Koskos has been a member of the Athens Bar Association since 1970 and is currently President of Hellenic American University in New Hampshire, USA. He served as President of the Board of Directors of the Hellenic American Union from 2020 to April 2023 and as its Managing Director from 1995 to 2012. Koskos has also held executive roles in major Greek and European companies, including APCO SA and EVGA SA.

He has served as President of the Association of Greek Food Industries and the European Association of Agricultural Industries and holds extensive experience in corporate management.