"The VIP boxes are now full. Chairman of the ICWQC, Mentor Metaxas, chats to the President of the Argentinian Council of Magic, Valentina Vazquez...."
-- Rita Skeeter reporting from the 2014 Quidditch World Cup final (Pm)
Mentor Metaxas was Chairman of the International Confederation of Wizards Quidditch Committee (ICWQC) in 2014 (Pm).
Mentor is a Greek name deriving from μενος (menos) meaning "mind, purpose, strength, courage". In Greek legend Mentor was the son of Alkimos and associate of Odysseus (Behind the Name).
Metaxas is a Greek name (Metaxās or Metaxa) meaning "silk grower or trader" (Wikipedia). Several famous Greek people have the surname Metaxas, including the dictator, general and Prime Minister Ioannis Metaxas.
With such a Greek name, it is likely that Chairman Metaxas is either from Greece or of Greek ancestry. With the famous Harry Potter, friends and family in the VIP Box 2, the crowd attending the final match probably haven't even noticed the other VIP guests....
Lexicon list of International Government Officials
From the Web
Writing by J.K. Rowling on Pottermore:
Pottermore enhanced reading experience: Quidditch World Cup
Screenshots of the original Daily Prophet coverage of the 2014 Quidditch World Cup on Pottermore: Imgur archive
Harry Potter Wiki: Mentor Metaxas