Why is king tutankhamun one of the most famous pharaohs in spite of the fact that he played such as small role in the history of egypt?

Well, first he is the youngest Egyptian pharaoh and he died after 10 years of ruling in  mysterious conditions. He also restored the old Egyptian  religion and his tomb was found completely intact, in difference to other tombs which were either destroyed because of their age or robbed. 
  

Sir thomas more, venerated in the catholic church as saint thomas more, was an english lawyer, social philosopher, author, statesman, and noted renaissance humanist. he was also a councillor to henry viii, and lord high chancellor of england from october 1529 to 16 may 1532. i found this information on wikipedia