David Cameron resigned last June after losing a referendum where Britain chose to leave the European Union.
Barack Obama is leaving the White House in January after a shock vote last month where the Republican nominee Donald Trump was elected the next president.
ChancellorAngela Merkel is facing a key election early next year. Apart from new opponents on the left, Merkel has to deal with a growing support for anti-euro and anti-European populism parties and criticism over her refugee policy.
Francois Hollande announced last week that he would not seek a second term as French president given his low popularity among the electorate.
Matteo Renzi is handing in his resignation to the Italian president on Monday after losing a key constitutional referendum.
Follow CNBC International on Twitter and Facebook.