He succeeds Paul Maier, who has moved to head up the new Observatory on IP Enforcement at the Office, and will take up the post in October.
Margellos has been chair of the First Board and Third Board, handling trade marks and designs cases respectively, and also coordinated the OHIM mediation team.
He has studied in Greece, France and Germany and has previously worked at the Court of Justice of the EU and the European Commission. He has also worked as an IP lawyer and taught law at the University of Picardie Jules Verne in Amiens.